Same, happens on loading the v4l2loopback module:

[ 1039.168432] v4l2loopback driver version 0.12.3 loaded
[ 1039.172977] ------------[ cut here ]------------
[ 1039.172994] WARNING: CPU: 3 PID: 8520 at drivers/media/v4l2-core/v4l2-ioctl.c:1064 v4l_querycap+0x8b/0xa0 [videodev]
[ 1039.172995] Modules linked in: v4l2loopback(OE) snd_seq_dummy iptable_mangle xt_CHECKSUM iptable_nat xt_MASQUERADE nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c xt_tcpudp bridge stp llc iptable_filter bpfilter binfmt_misc nls_iso8859_1 snd_hda_codec_realtek snd_hda_codec_generic ledtrig_audio snd_hda_codec_hdmi edac_mce_amd snd_hda_intel snd_intel_dspcfg kvm_amd snd_hda_codec ccp snd_hda_core snd_usb_audio kvm snd_usbmidi_lib snd_hwdep serio_raw snd_pcm fam15h_power k10temp snd_seq_midi snd_seq_midi_event snd_rawmidi gspca_zc3xx gspca_vc032x uvcvideo gspca_main snd_seq input_leds videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common joydev videodev snd_seq_device mc cdc_acm snd_timer snd soundcore mac_hid sch_fq_codel parport_pc ppdev lp parport ip_tables x_tables autofs4 dm_crypt amdgpu amd_iommu_v2 gpu_sched uas usb_storage hid_generic usbhid hid crct10dif_pclmul crc32_pclmul ghash_clmulni_intel radeon i2c_algo_bit ttm aesni_intel crypto_simd drm_kms_helper
[ 1039.173027]  cryptd syscopyarea glue_helper sysfillrect sysimgblt fb_sys_fops i2c_piix4 ahci drm libahci r8169 realtek video [last unloaded: v4l2loopback]
[ 1039.173035] CPU: 3 PID: 8520 Comm: v4l_id Tainted: G        W  OE     5.4.0-29-generic #33-Ubuntu
[ 1039.173036] Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./G1.Sniper A88X-CF, BIOS F7 01/08/2014
[ 1039.173042] RIP: 0010:v4l_querycap+0x8b/0xa0 [videodev]
[ 1039.173044] Code: 54 81 ca 00 00 00 80 48 b9 00 00 20 00 00 00 20 00 48 0b 4b 54 21 d6 39 f2 75 13 48 89 4b 54 5b 41 5c 41 5d 41 5e 41 5f 5d c3 <0f> 0b eb d0 0f 0b 48 89 4b 54 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f
[ 1039.173045] RSP: 0018:ffffbc64429c3c70 EFLAGS: 00010297
[ 1039.173047] RAX: 0000000000000000 RBX: ffffbc64429c3d88 RCX: 0000000000000001
[ 1039.173048] RDX: 0000000085008003 RSI: 0000000000000000 RDI: 0000000000000000
[ 1039.173048] RBP: ffffbc64429c3c98 R08: 0000000000000000 R09: 0000000000ffff0a
[ 1039.173049] R10: 0000000000000000 R11: 0000000000000000 R12: ffff92f309255000
[ 1039.173050] R13: ffff92f317d7e200 R14: ffff92f234abe6a0 R15: ffffffffc0fd8380
[ 1039.173052] FS:  00007fc41b97e580(0000) GS:ffff92f31fb80000(0000) knlGS:0000000000000000
[ 1039.173053] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1039.173053] CR2: 00007fc41b830cc0 CR3: 00000007a7e00000 CR4: 00000000000406e0
[ 1039.173054] Call Trace:
[ 1039.173064]  __video_do_ioctl+0x1a7/0x410 [videodev]
[ 1039.173070]  video_usercopy+0x2b5/0x670 [videodev]
[ 1039.173076]  ? v4l_s_fmt+0x670/0x670 [videodev]
[ 1039.173082]  video_ioctl2+0x15/0x20 [videodev]
[ 1039.173087]  v4l2_ioctl+0x4c/0x60 [videodev]
[ 1039.173091]  do_vfs_ioctl+0x407/0x670
[ 1039.173095]  ? __secure_computing+0x42/0xe0
[ 1039.173096]  ksys_ioctl+0x67/0x90
[ 1039.173098]  __x64_sys_ioctl+0x1a/0x20
[ 1039.173100]  do_syscall_64+0x57/0x190
[ 1039.173103]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 1039.173105] RIP: 0033:0x7fc41b83737b
[ 1039.173107] Code: 0f 1e fa 48 8b 05 15 3b 0d 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e5 3a 0d 00 f7 d8 64 89 01 48
[ 1039.173108] RSP: 002b:00007ffd63439488 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[ 1039.173109] RAX: ffffffffffffffda RBX: 00007ffd63439608 RCX: 00007fc41b83737b
[ 1039.173110] RDX: 00007ffd63439490 RSI: 0000000080685600 RDI: 0000000000000003
[ 1039.173110] RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
[ 1039.173111] R10: 0000000000000000 R11: 0000000000000246 R12: 000055a68fffa440
[ 1039.173112] R13: 00007ffd63439600 R14: 0000000000000000 R15: 0000000000000000
[ 1039.173114] ---[ end trace d94124d807433b7d ]---
[ 1039.173126] ------------[ cut here ]------------
[ 1039.173132] WARNING: CPU: 3 PID: 8520 at drivers/media/v4l2-core/v4l2-ioctl.c:1069 v4l_querycap+0x8f/0xa0 [videodev]
[ 1039.173132] Modules linked in: v4l2loopback(OE) snd_seq_dummy iptable_mangle xt_CHECKSUM iptable_nat xt_MASQUERADE nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c xt_tcpudp bridge stp llc iptable_filter bpfilter binfmt_misc nls_iso8859_1 snd_hda_codec_realtek snd_hda_codec_generic ledtrig_audio snd_hda_codec_hdmi edac_mce_amd snd_hda_intel snd_intel_dspcfg kvm_amd snd_hda_codec ccp snd_hda_core snd_usb_audio kvm snd_usbmidi_lib snd_hwdep serio_raw snd_pcm fam15h_power k10temp snd_seq_midi snd_seq_midi_event snd_rawmidi gspca_zc3xx gspca_vc032x uvcvideo gspca_main snd_seq input_leds videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common joydev videodev snd_seq_device mc cdc_acm snd_timer snd soundcore mac_hid sch_fq_codel parport_pc ppdev lp parport ip_tables x_tables autofs4 dm_crypt amdgpu amd_iommu_v2 gpu_sched uas usb_storage hid_generic usbhid hid crct10dif_pclmul crc32_pclmul ghash_clmulni_intel radeon i2c_algo_bit ttm aesni_intel crypto_simd drm_kms_helper
[ 1039.173153]  cryptd syscopyarea glue_helper sysfillrect sysimgblt fb_sys_fops i2c_piix4 ahci drm libahci r8169 realtek video [last unloaded: v4l2loopback]
[ 1039.173158] CPU: 3 PID: 8520 Comm: v4l_id Tainted: G        W  OE     5.4.0-29-generic #33-Ubuntu
[ 1039.173158] Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./G1.Sniper A88X-CF, BIOS F7 01/08/2014
[ 1039.173164] RIP: 0010:v4l_querycap+0x8f/0xa0 [videodev]
[ 1039.173165] Code: 00 00 80 48 b9 00 00 20 00 00 00 20 00 48 0b 4b 54 21 d6 39 f2 75 13 48 89 4b 54 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 0b eb d0 <0f> 0b 48 89 4b 54 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 1f 44 00 00
[ 1039.173166] RSP: 0018:ffffbc64429c3c70 EFLAGS: 00010202
[ 1039.173167] RAX: 0000000000000000 RBX: ffffbc64429c3d88 RCX: 8520800285208002
[ 1039.173168] RDX: 0000000085008003 RSI: 0000000085008002 RDI: 0000000000000000
[ 1039.173169] RBP: ffffbc64429c3c98 R08: 0000000000000000 R09: 0000000000ffff0a
[ 1039.173170] R10: 0000000000000000 R11: 0000000000000000 R12: ffff92f309255000
[ 1039.173171] R13: ffff92f317d7e200 R14: ffff92f234abe6a0 R15: ffffffffc0fd8380
[ 1039.173172] FS:  00007fc41b97e580(0000) GS:ffff92f31fb80000(0000) knlGS:0000000000000000
[ 1039.173173] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1039.173174] CR2: 00007fc41b830cc0 CR3: 00000007a7e00000 CR4: 00000000000406e0
[ 1039.173175] Call Trace:
[ 1039.173180]  __video_do_ioctl+0x1a7/0x410 [videodev]
[ 1039.173186]  video_usercopy+0x2b5/0x670 [videodev]
[ 1039.173192]  ? v4l_s_fmt+0x670/0x670 [videodev]
[ 1039.173198]  video_ioctl2+0x15/0x20 [videodev]
[ 1039.173202]  v4l2_ioctl+0x4c/0x60 [videodev]
[ 1039.173204]  do_vfs_ioctl+0x407/0x670
[ 1039.173207]  ? __secure_computing+0x42/0xe0
[ 1039.173208]  ksys_ioctl+0x67/0x90
[ 1039.173210]  __x64_sys_ioctl+0x1a/0x20
[ 1039.173211]  do_syscall_64+0x57/0x190
[ 1039.173213]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 1039.173214] RIP: 0033:0x7fc41b83737b
[ 1039.173216] Code: 0f 1e fa 48 8b 05 15 3b 0d 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e5 3a 0d 00 f7 d8 64 89 01 48
[ 1039.173217] RSP: 002b:00007ffd63439488 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[ 1039.173218] RAX: ffffffffffffffda RBX: 00007ffd63439608 RCX: 00007fc41b83737b
[ 1039.173219] RDX: 00007ffd63439490 RSI: 0000000080685600 RDI: 0000000000000003
[ 1039.173219] RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000
[ 1039.173220] R10: 0000000000000000 R11: 0000000000000246 R12: 000055a68fffa440
[ 1039.173221] R13: 00007ffd63439600 R14: 0000000000000000 R15: 0000000000000000
[ 1039.173222] ---[ end trace d94124d807433b7e ]---

I get more or less the same traces again if I then start the v4l2sink in OBS Studio:

[ 1534.189944] ------------[ cut here ]------------
[ 1534.189983] WARNING: CPU: 1 PID: 9882 at drivers/media/v4l2-core/v4l2-ioctl.c:1064 v4l_querycap+0x8b/0xa0 [videodev]
[ 1534.189984] Modules linked in: v4l2loopback(OE) snd_seq_dummy iptable_mangle xt_CHECKSUM iptable_nat xt_MASQUERADE nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c xt_tcpudp bridge stp llc iptable_filter bpfilter binfmt_misc nls_iso8859_1 snd_hda_codec_realtek snd_hda_codec_generic ledtrig_audio snd_hda_codec_hdmi edac_mce_amd snd_hda_intel snd_intel_dspcfg kvm_amd snd_hda_codec ccp snd_hda_core snd_usb_audio kvm snd_usbmidi_lib snd_hwdep serio_raw snd_pcm fam15h_power k10temp snd_seq_midi snd_seq_midi_event snd_rawmidi gspca_zc3xx gspca_vc032x uvcvideo gspca_main snd_seq input_leds videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common joydev videodev snd_seq_device mc cdc_acm snd_timer snd soundcore mac_hid sch_fq_codel parport_pc ppdev lp parport ip_tables x_tables autofs4 dm_crypt amdgpu amd_iommu_v2 gpu_sched uas usb_storage hid_generic usbhid hid crct10dif_pclmul crc32_pclmul ghash_clmulni_intel radeon i2c_algo_bit ttm aesni_intel crypto_simd drm_kms_helper
[ 1534.190019]  cryptd syscopyarea glue_helper sysfillrect sysimgblt fb_sys_fops i2c_piix4 ahci drm libahci r8169 realtek video [last unloaded: v4l2loopback]
[ 1534.190030] CPU: 1 PID: 9882 Comm: obs Tainted: G        W  OE     5.4.0-29-generic #33-Ubuntu
[ 1534.190031] Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./G1.Sniper A88X-CF, BIOS F7 01/08/2014
[ 1534.190037] RIP: 0010:v4l_querycap+0x8b/0xa0 [videodev]
[ 1534.190039] Code: 54 81 ca 00 00 00 80 48 b9 00 00 20 00 00 00 20 00 48 0b 4b 54 21 d6 39 f2 75 13 48 89 4b 54 5b 41 5c 41 5d 41 5e 41 5f 5d c3 <0f> 0b eb d0 0f 0b 48 89 4b 54 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f
[ 1534.190040] RSP: 0018:ffffbc6442973c70 EFLAGS: 00010293
[ 1534.190041] RAX: 0000000000000000 RBX: ffffbc6442973d88 RCX: 0000000000000000
[ 1534.190042] RDX: 0000000085008003 RSI: 0000000000000000 RDI: 0000000000000000
[ 1534.190043] RBP: ffffbc6442973c98 R08: 0000000000000000 R09: 0000000000ffff0a
[ 1534.190043] R10: 0000000000000000 R11: 0000000000000000 R12: ffff92f309255000
[ 1534.190044] R13: ffff92f314284600 R14: ffff92f315fc96a0 R15: ffffffffc0fd8380
[ 1534.190045] FS:  00007f518ceedf00(0000) GS:ffff92f31fa80000(0000) knlGS:0000000000000000
[ 1534.190046] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1534.190047] CR2: 00007f5aae1a2000 CR3: 000000077def6000 CR4: 00000000000406e0
[ 1534.190048] Call Trace:
[ 1534.190057]  __video_do_ioctl+0x1a7/0x410 [videodev]
[ 1534.190062]  video_usercopy+0x2b5/0x670 [videodev]
[ 1534.190067]  ? v4l_s_fmt+0x670/0x670 [videodev]
[ 1534.190072]  video_ioctl2+0x15/0x20 [videodev]
[ 1534.190076]  v4l2_ioctl+0x4c/0x60 [videodev]
[ 1534.190080]  do_vfs_ioctl+0x407/0x670
[ 1534.190084]  ? putname+0x4a/0x50
[ 1534.190085]  ksys_ioctl+0x67/0x90
[ 1534.190086]  __x64_sys_ioctl+0x1a/0x20
[ 1534.190090]  do_syscall_64+0x57/0x190
[ 1534.190093]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 1534.190095] RIP: 0033:0x7f518d02737b
[ 1534.190096] Code: 0f 1e fa 48 8b 05 15 3b 0d 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e5 3a 0d 00 f7 d8 64 89 01 48
[ 1534.190097] RSP: 002b:00007ffce69e4028 EFLAGS: 00000206 ORIG_RAX: 0000000000000010
[ 1534.190098] RAX: ffffffffffffffda RBX: 000055ba74163e80 RCX: 00007f518d02737b
[ 1534.190098] RDX: 00007ffce69e4090 RSI: 0000000080685600 RDI: 0000000000000027
[ 1534.190099] RBP: 00007ffce69e41e0 R08: 000000000000ffff R09: 000000000000003f
[ 1534.190100] R10: 00007f518d077020 R11: 0000000000000206 R12: 0000000000000029
[ 1534.190100] R13: 00007f5125354044 R14: 00007ffce69e4490 R15: 00007f518d9cfe68
[ 1534.190102] ---[ end trace d94124d807433b83 ]---
[ 1534.190135] ------------[ cut here ]------------
[ 1534.190140] WARNING: CPU: 1 PID: 9882 at drivers/media/v4l2-core/v4l2-ioctl.c:1069 v4l_querycap+0x8f/0xa0 [videodev]
[ 1534.190141] Modules linked in: v4l2loopback(OE) snd_seq_dummy iptable_mangle xt_CHECKSUM iptable_nat xt_MASQUERADE nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c xt_tcpudp bridge stp llc iptable_filter bpfilter binfmt_misc nls_iso8859_1 snd_hda_codec_realtek snd_hda_codec_generic ledtrig_audio snd_hda_codec_hdmi edac_mce_amd snd_hda_intel snd_intel_dspcfg kvm_amd snd_hda_codec ccp snd_hda_core snd_usb_audio kvm snd_usbmidi_lib snd_hwdep serio_raw snd_pcm fam15h_power k10temp snd_seq_midi snd_seq_midi_event snd_rawmidi gspca_zc3xx gspca_vc032x uvcvideo gspca_main snd_seq input_leds videobuf2_vmalloc videobuf2_memops videobuf2_v4l2 videobuf2_common joydev videodev snd_seq_device mc cdc_acm snd_timer snd soundcore mac_hid sch_fq_codel parport_pc ppdev lp parport ip_tables x_tables autofs4 dm_crypt amdgpu amd_iommu_v2 gpu_sched uas usb_storage hid_generic usbhid hid crct10dif_pclmul crc32_pclmul ghash_clmulni_intel radeon i2c_algo_bit ttm aesni_intel crypto_simd drm_kms_helper
[ 1534.190157]  cryptd syscopyarea glue_helper sysfillrect sysimgblt fb_sys_fops i2c_piix4 ahci drm libahci r8169 realtek video [last unloaded: v4l2loopback]
[ 1534.190161] CPU: 1 PID: 9882 Comm: obs Tainted: G        W  OE     5.4.0-29-generic #33-Ubuntu
[ 1534.190161] Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./G1.Sniper A88X-CF, BIOS F7 01/08/2014
[ 1534.190166] RIP: 0010:v4l_querycap+0x8f/0xa0 [videodev]
[ 1534.190167] Code: 00 00 80 48 b9 00 00 20 00 00 00 20 00 48 0b 4b 54 21 d6 39 f2 75 13 48 89 4b 54 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 0b eb d0 <0f> 0b 48 89 4b 54 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 1f 44 00 00
[ 1534.190168] RSP: 0018:ffffbc6442973c70 EFLAGS: 00010206
[ 1534.190169] RAX: 0000000000000000 RBX: ffffbc6442973d88 RCX: 8520800085208000
[ 1534.190169] RDX: 0000000085008003 RSI: 0000000085008000 RDI: 0000000000000000
[ 1534.190170] RBP: ffffbc6442973c98 R08: 0000000000000000 R09: 0000000000ffff0a
[ 1534.190170] R10: 0000000000000000 R11: 0000000000000000 R12: ffff92f309255000
[ 1534.190171] R13: ffff92f314284600 R14: ffff92f315fc96a0 R15: ffffffffc0fd8380
[ 1534.190172] FS:  00007f518ceedf00(0000) GS:ffff92f31fa80000(0000) knlGS:0000000000000000
[ 1534.190173] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1534.190174] CR2: 00007f5aae1a2000 CR3: 000000077def6000 CR4: 00000000000406e0
[ 1534.190174] Call Trace:
[ 1534.190179]  __video_do_ioctl+0x1a7/0x410 [videodev]
[ 1534.190184]  video_usercopy+0x2b5/0x670 [videodev]
[ 1534.190188]  ? v4l_s_fmt+0x670/0x670 [videodev]
[ 1534.190193]  video_ioctl2+0x15/0x20 [videodev]
[ 1534.190197]  v4l2_ioctl+0x4c/0x60 [videodev]
[ 1534.190198]  do_vfs_ioctl+0x407/0x670
[ 1534.190200]  ? putname+0x4a/0x50
[ 1534.190201]  ksys_ioctl+0x67/0x90
[ 1534.190202]  __x64_sys_ioctl+0x1a/0x20
[ 1534.190204]  do_syscall_64+0x57/0x190
[ 1534.190205]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 1534.190206] RIP: 0033:0x7f518d02737b
[ 1534.190207] Code: 0f 1e fa 48 8b 05 15 3b 0d 00 64 c7 00 26 00 00 00 48 c7 c0 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d e5 3a 0d 00 f7 d8 64 89 01 48
[ 1534.190208] RSP: 002b:00007ffce69e4028 EFLAGS: 00000206 ORIG_RAX: 0000000000000010
[ 1534.190209] RAX: ffffffffffffffda RBX: 000055ba74163e80 RCX: 00007f518d02737b
[ 1534.190209] RDX: 00007ffce69e4090 RSI: 0000000080685600 RDI: 0000000000000027
[ 1534.190210] RBP: 00007ffce69e41e0 R08: 000000000000ffff R09: 000000000000003f
[ 1534.190210] R10: 00007f518d077020 R11: 0000000000000206 R12: 0000000000000029
[ 1534.190211] R13: 00007f5125354044 R14: 00007ffce69e4490 R15: 00007f518d9cfe68
[ 1534.190212] ---[ end trace d94124d807433b84 ]---

Maybe the culprit is one of these:

$ LANG=C dpkg -l v4l2loopback-*
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name                 Version      Architecture Description
+++-====================-============-============-==========================================================
ii  v4l2loopback-dkms    0.12.3-1     all          Source for the v4l2loopback driver (DKMS)
un  v4l2loopback-modules <none>       <none>       (no description available)
ii  v4l2loopback-utils   0.12.3-1     all          Commandline utilities for the for the v4l2-loopback module


And no, I cannot test with the most recent 5.4.0-31 kernel as the boot partition created six years ago is too small to update a kernel if two current kernels (-generic and -lowlatency) are already installed. Even with compression = xz. And I'll retire the system later today, I'll report back if the issue persists on ryzen based systems.