Linux Mint 20.1 Ulyssa
Firefox 89.0

after update, i got ff 89, i have messages like this in syslog, on every start of firefox:

Jun 20 15:24:23 dinar-Lenovo-G580 wpa_supplicant[680]: wlp2s0: CTRL-EVENT-SIGNAL-CHANGE above=0 signal=-80 noise=-95 txrate=43300
Jun 20 15:25:21 dinar-Lenovo-G580 kernel: [22164.956789] audit: type=1400 audit(1624191921.071:165): apparmor="DENIED" operation="open" profile="firefox" name="/sys/devices/pci0000:00/0000:00:1f.2/resource" pid=15814 comm="firefox" requested_mask="r" denied_mask="r" fsuid=1000 ouid=0
Jun 20 15:25:21 dinar-Lenovo-G580 kernel: [22164.956816] firefox[15814]: segfault at 0 ip 00007ff585b5ad94 sp 00007ffceca77710 error 6 in libxul.so[7ff582318000+5392000]
Jun 20 15:25:21 dinar-Lenovo-G580 kernel: [22164.956822] Code: 00 e8 28 69 7c fc 50 80 3d f8 0b 4e 04 00 74 02 58 c3 c6 05 ed 0b 4e 04 01 48 8d 05 29 15 fc 02 48 8b 0d 47 36 3c 04 48 89 01 <c7> 04 25 00 00 00 00 8b 01 00 00 e8 f4 68 7c fc 66 2e 0f 1f 84 00
Jun 20 15:25:21 dinar-Lenovo-G580 systemd[1]: Started Process Core Dump (PID 15815/UID 0).
Jun 20 15:25:21 dinar-Lenovo-G580 kernel: [22164.998424] audit: type=1400 audit(1624191921.111:166): apparmor="DENIED" operation="open" profile="firefox" name="/run/user/1000/ICEauthority" pid=15809 comm="firefox" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000
Jun 20 15:25:21 dinar-Lenovo-G580 systemd-coredump[15816]: Process 15814 (firefox) of user 1000 dumped core.#012#012Stack trace of thread 15814:#012#0  0x00007ff585b5ad94 n/a (libxul.so + 0x4185d94)#012#1  0x00007ff58ca19a27 __run_exit_handlers (libc.so.6 + 0x49a27)#012#2  0x00007ff58ca19be0 __GI_exit (libc.so.6 + 0x49be0)#012#3  0x00007ff5816f6c45 n/a (libpci.so.3 + 0x3c45)#012#4  0x00007ff5816fc308 n/a (libpci.so.3 + 0x9308)#012#5  0x00007ff585b64054 n/a (libxul.so + 0x418f054)#012#6  0x00007ff585b649db n/a (libxul.so + 0x418f9db)#012#7  0x00007ff585b5a13e n/a (libxul.so + 0x418513e)#012#8  0x00007ff585b60ae3 n/a (libxul.so + 0x418bae3)#012#9  0x00007ff585b60ee0 n/a (libxul.so + 0x418bee0)#012#10 0x0000556820bc9113 n/a (firefox + 0xc113)#012#11 0x00007ff58c9f70b3 __libc_start_main (libc.so.6 + 0x270b3)#012#12 0x0000556820bc8b6e _start (firefox + 0xbb6e)
Jun 20 15:25:21 dinar-Lenovo-G580 systemd[1]: systemd-coredump@8-15815-0.service: Succeeded.
Jun 20 15:25:21 dinar-Lenovo-G580 kernel: [22165.724715] audit: type=1400 audit(1624191921.839:167): apparmor="DENIED" operation="open" profile="firefox" name="/proc/15809/cgroup" pid=15809 comm="firefox" requested_mask="r" denied_mask="r" fsuid=1000 ouid=1000
Jun 20 15:25:21 dinar-Lenovo-G580 kernel: [22165.862576] audit: type=1107 audit(1624191921.975:168): pid=657 uid=103 auid=4294967295 ses=4294967295 msg='apparmor="DENIED" operation="dbus_method_call"  bus="system" path="/org/freedesktop/RealtimeKit1" interface="org.freedesktop.DBus.Properties" member="Get" mask="send" name="org.freedesktop.RealtimeKit1" pid=15895 label="firefox" peer_pid=978 peer_label="unconfined"
Jun 20 15:25:21 dinar-Lenovo-G580 kernel: [22165.862576]  exe="/usr/bin/dbus-daemon" sauid=103 hostname=? addr=? terminal=?'
Jun 20 15:25:22 dinar-Lenovo-G580 kernel: [22166.090862] audit: type=1107 audit(1624191922.207:169): pid=657 uid=103 auid=4294967295 ses=4294967295 msg='apparmor="DENIED" operation="dbus_method_call"  bus="system" path="/org/freedesktop/RealtimeKit1" interface="org.freedesktop.DBus.Properties" member="Get" mask="send" name="org.freedesktop.RealtimeKit1" pid=15809 label="firefox" peer_pid=978 peer_label="unconfined"
Jun 20 15:25:22 dinar-Lenovo-G580 kernel: [22166.090862]  exe="/usr/bin/dbus-daemon" sauid=103 hostname=? addr=? terminal=?'
Jun 20 15:25:22 dinar-Lenovo-G580 kernel: [22166.676720] audit: type=1107 audit(1624191922.791:170): pid=657 uid=103 auid=4294967295 ses=4294967295 msg='apparmor="DENIED" operation="dbus_method_call"  bus="system" path="/org/freedesktop/RealtimeKit1" interface="org.freedesktop.DBus.Properties" member="Get" mask="send" name="org.freedesktop.RealtimeKit1" pid=15973 label="firefox" peer_pid=978 peer_label="unconfined"
Jun 20 15:25:22 dinar-Lenovo-G580 kernel: [22166.676720]  exe="/usr/bin/dbus-daemon" sauid=103 hostname=? addr=? terminal=?'
Jun 20 15:25:23 dinar-Lenovo-G580 kernel: [22167.484270] audit: type=1107 audit(1624191923.599:171): pid=657 uid=103 auid=4294967295 ses=4294967295 msg='apparmor="DENIED" operation="dbus_method_call"  bus="system" path="/org/freedesktop/RealtimeKit1" interface="org.freedesktop.DBus.Properties" member="Get" mask="send" name="org.freedesktop.RealtimeKit1" pid=16038 label="firefox" peer_pid=978 peer_label="unconfined"
Jun 20 15:25:23 dinar-Lenovo-G580 kernel: [22167.484270]  exe="/usr/bin/dbus-daemon" sauid=103 hostname=? addr=? terminal=?'
Jun 20 15:25:25 dinar-Lenovo-G580 kernel: [22169.310779] audit: type=1107 audit(1624191925.427:172): pid=657 uid=103 auid=4294967295 ses=4294967295 msg='apparmor="DENIED" operation="dbus_method_call"  bus="system" path="/org/freedesktop/RealtimeKit1" interface="org.freedesktop.DBus.Properties" member="Get" mask="send" name="org.freedesktop.RealtimeKit1" pid=16078 label="firefox" peer_pid=978 peer_label="unconfined"
Jun 20 15:25:25 dinar-Lenovo-G580 kernel: [22169.310779]  exe="/usr/bin/dbus-daemon" sauid=103 hostname=? addr=? terminal=?'
Jun 20 15:26:17 dinar-Lenovo-G580 wpa_supplicant[680]: wlp2s0: CTRL-EVENT-SIGNAL-CHANGE above=1 signal=-67 noise=-95 txrate=39000

there is segfault, and i reported it to https://bugzilla.mozilla.org/show_bug.cgi?id=1717332 .