Sorry, more info... looking at kern.log, the context is as follows. Note that this occurred when the machine had auto-suspended with the laptop open, and the black screen with text was already visible when I came into the room. It did not suddenly appear as a result of my triggering a return from suspend. At the end you can see the beginning of the power off process I started by pressing the power button.

Jul 14 22:58:14 Hebegb kernel: [ 6874.519984] CPU2: Core temperature above threshold, cpu clock throttled (total events = 1621)
Jul 14 22:58:14 Hebegb kernel: [ 6874.519985] CPU6: Core temperature above threshold, cpu clock throttled (total events = 1621)
Jul 14 22:58:14 Hebegb kernel: [ 6874.519987] CPU6: Package temperature above threshold, cpu clock throttled (total events = 4509)
Jul 14 22:58:14 Hebegb kernel: [ 6874.519988] CPU2: Package temperature above threshold, cpu clock throttled (total events = 4509)
Jul 14 22:58:14 Hebegb kernel: [ 6874.520032] CPU5: Package temperature above threshold, cpu clock throttled (total events = 4509)
Jul 14 22:58:14 Hebegb kernel: [ 6874.520033] CPU0: Package temperature above threshold, cpu clock throttled (total events = 4509)
Jul 14 22:58:14 Hebegb kernel: [ 6874.520034] CPU1: Package temperature above threshold, cpu clock throttled (total events = 4509)
Jul 14 22:58:14 Hebegb kernel: [ 6874.520035] CPU4: Package temperature above threshold, cpu clock throttled (total events = 4509)
Jul 14 22:58:14 Hebegb kernel: [ 6874.520036] CPU3: Package temperature above threshold, cpu clock throttled (total events = 4509)
Jul 14 22:58:14 Hebegb kernel: [ 6874.520036] CPU7: Package temperature above threshold, cpu clock throttled (total events = 4509)
Jul 14 22:58:14 Hebegb kernel: [ 6874.520983] CPU2: Core temperature/speed normal
Jul 14 22:58:14 Hebegb kernel: [ 6874.520983] CPU6: Core temperature/speed normal
Jul 14 22:58:14 Hebegb kernel: [ 6874.520984] CPU6: Package temperature/speed normal
Jul 14 22:58:14 Hebegb kernel: [ 6874.520985] CPU2: Package temperature/speed normal
Jul 14 22:58:14 Hebegb kernel: [ 6874.521029] CPU0: Package temperature/speed normal
Jul 14 22:58:14 Hebegb kernel: [ 6874.521030] CPU5: Package temperature/speed normal
Jul 14 22:58:14 Hebegb kernel: [ 6874.521030] CPU1: Package temperature/speed normal
Jul 14 22:58:14 Hebegb kernel: [ 6874.521031] CPU4: Package temperature/speed normal
Jul 14 22:58:14 Hebegb kernel: [ 6874.521032] CPU3: Package temperature/speed normal
Jul 14 22:58:14 Hebegb kernel: [ 6874.521032] CPU7: Package temperature/speed normal
Jul 14 22:58:25 Hebegb kernel: [ 6885.747439] wlo1: deauthenticating from 7a:ad:ec:af:0c:36 by local choice (Reason: 3=DEAUTH_LEAVING)
Jul 14 22:58:25 Hebegb kernel: [ 6886.034734] PM: suspend entry (deep)
Jul 14 22:58:25 Hebegb kernel: [ 6886.034735] PM: Syncing filesystems ... done.
Jul 14 23:00:16 Hebegb kernel: [ 6886.915305] Freezing user space processes ... (elapsed 0.002 seconds) done.
Jul 14 23:00:16 Hebegb kernel: [ 6886.917622] OOM killer disabled.
Jul 14 23:00:16 Hebegb kernel: [ 6886.917622] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.
Jul 14 23:00:16 Hebegb kernel: [ 6886.918949] Suspending console(s) (use no_console_suspend to debug)
Jul 14 23:00:16 Hebegb kernel: [ 6887.403105] ACPI: EC: interrupt blocked
Jul 14 23:00:16 Hebegb kernel: [ 6887.458786] ACPI: Preparing to enter system sleep state S3
Jul 14 23:00:16 Hebegb kernel: [ 6887.472912] ACPI: EC: event blocked
Jul 14 23:00:16 Hebegb kernel: [ 6887.472914] ACPI: EC: EC stopped
Jul 14 23:00:16 Hebegb kernel: [ 6887.472915] PM: Saving platform NVS memory
Jul 14 23:00:16 Hebegb kernel: [ 6887.472998] Disabling non-boot CPUs ...
Jul 14 23:00:16 Hebegb kernel: [ 6887.487497] smpboot: CPU 1 is now offline
Jul 14 23:00:16 Hebegb kernel: [ 6887.511483] smpboot: CPU 2 is now offline
Jul 14 23:00:16 Hebegb kernel: [ 6887.539439] smpboot: CPU 3 is now offline
Jul 14 23:00:16 Hebegb kernel: [ 6887.556517] smpboot: CPU 4 is now offline
Jul 14 23:00:16 Hebegb kernel: [ 6887.578240] IRQ 123: no longer affine to CPU5
Jul 14 23:00:16 Hebegb kernel: [ 6887.579269] smpboot: CPU 5 is now offline
Jul 14 23:00:16 Hebegb kernel: [ 6887.603248] smpboot: CPU 6 is now offline
Jul 14 23:00:16 Hebegb kernel: [ 6887.626205] IRQ 132: no longer affine to CPU7
Jul 14 23:00:16 Hebegb kernel: [ 6887.626214] IRQ 133: no longer affine to CPU7
Jul 14 23:00:16 Hebegb kernel: [ 6887.626227] IRQ 148: no longer affine to CPU7
Jul 14 23:00:16 Hebegb kernel: [ 6887.627246] smpboot: CPU 7 is now offline
Jul 14 23:00:16 Hebegb kernel: [ 6887.631198] ACPI: Low-level resume complete
Jul 14 23:00:16 Hebegb kernel: [ 6887.631276] ACPI: EC: EC started
Jul 14 23:00:16 Hebegb kernel: [ 6887.631277] PM: Restoring platform NVS memory
Jul 14 23:00:16 Hebegb kernel: [ 6887.633788] Enabling non-boot CPUs ...
Jul 14 23:00:16 Hebegb kernel: [ 6887.633826] x86: Booting SMP configuration:
Jul 14 23:00:16 Hebegb kernel: [ 6887.633827] smpboot: Booting Node 0 Processor 1 APIC 0x2
Jul 14 23:00:16 Hebegb kernel: [ 6887.635896]  cache: parent cpu1 should not be sleeping
Jul 14 23:00:16 Hebegb kernel: [ 6887.635988] microcode: sig=0x806ea, pf=0x80, revision=0xb4
Jul 14 23:00:16 Hebegb kernel: [ 6887.637644] microcode: updated to revision 0xd6, date = 2020-04-27
Jul 14 23:00:16 Hebegb kernel: [ 6887.637734] CPU1 is up
Jul 14 23:00:16 Hebegb kernel: [ 6887.637777] smpboot: Booting Node 0 Processor 2 APIC 0x4
Jul 14 23:00:16 Hebegb kernel: [ 6887.638272]  cache: parent cpu2 should not be sleeping
Jul 14 23:00:16 Hebegb kernel: [ 6887.640127] CPU2 is up
Jul 14 23:00:16 Hebegb kernel: [ 6887.640152] smpboot: Booting Node 0 Processor 3 APIC 0x6
Jul 14 23:00:16 Hebegb kernel: [ 6887.640635]  cache: parent cpu3 should not be sleeping
Jul 14 23:00:16 Hebegb kernel: [ 6887.642440] CPU3 is up
Jul 14 23:00:16 Hebegb kernel: [ 6887.642463] smpboot: Booting Node 0 Processor 4 APIC 0x1
Jul 14 23:00:16 Hebegb kernel: [ 6887.643096]  cache: parent cpu4 should not be sleeping
Jul 14 23:00:16 Hebegb kernel: [ 6887.643186] microcode: sig=0x806ea, pf=0x80, revision=0xd6
Jul 14 23:00:16 Hebegb kernel: [ 6887.643290] CPU4 is up
Jul 14 23:00:16 Hebegb kernel: [ 6887.643317] smpboot: Booting Node 0 Processor 5 APIC 0x3
Jul 14 23:00:16 Hebegb kernel: [ 6887.643834]  cache: parent cpu5 should not be sleeping
Jul 14 23:00:16 Hebegb kernel: [ 6887.644036] CPU5 is up
Jul 14 23:00:16 Hebegb kernel: [ 6887.644057] smpboot: Booting Node 0 Processor 6 APIC 0x5
Jul 14 23:00:16 Hebegb kernel: [ 6887.644572]  cache: parent cpu6 should not be sleeping
Jul 14 23:00:16 Hebegb kernel: [ 6887.644783] CPU6 is up
Jul 14 23:00:16 Hebegb kernel: [ 6887.644805] smpboot: Booting Node 0 Processor 7 APIC 0x7
Jul 14 23:00:16 Hebegb kernel: [ 6887.645319]  cache: parent cpu7 should not be sleeping
Jul 14 23:00:16 Hebegb kernel: [ 6887.645546] CPU7 is up
Jul 14 23:00:16 Hebegb kernel: [ 6887.653369] ACPI: Waking up from system sleep state S3
Jul 14 23:00:16 Hebegb kernel: [ 6887.679434] ACPI: EC: interrupt unblocked
Jul 14 23:00:16 Hebegb kernel: [ 6887.747810] ACPI: EC: event unblocked
Jul 14 23:00:16 Hebegb kernel: [ 6887.757280] ACPI: button: The lid device is not compliant to SW_LID.
Jul 14 23:00:16 Hebegb kernel: [ 6887.981985] usb 1-7: reset full-speed USB device number 4 using xhci_hcd
Jul 14 23:00:16 Hebegb kernel: [ 6888.258058] usb 1-5: reset high-speed USB device number 3 using xhci_hcd
Jul 14 23:00:16 Hebegb kernel: [ 6888.682904] ish-hid {33AECD58-B679-4E54-9BD9-A04D34F0C226}: [hid-ish]: enum_devices_done OK, num_hid_devices=4
Jul 14 23:00:16 Hebegb kernel: [ 6888.698055] psmouse serio1: synaptics: queried max coordinates: x [..5612], y [..4708]
Jul 14 23:00:16 Hebegb kernel: [ 6888.737063] psmouse serio1: synaptics: queried min coordinates: x [1330..], y [1146..]
Jul 14 23:00:16 Hebegb kernel: [ 6891.466081] hid-sensor-hub 001F:8086:22D8.0005: timeout waiting for response from ISHTP device
Jul 14 23:00:16 Hebegb kernel: [ 6891.466128] hid-sensor-hub 001F:8086:22D8.0004: timeout waiting for response from ISHTP device
Jul 14 23:00:16 Hebegb kernel: [ 6891.806877] NVRM: GPU at PCI:0000:01:00: GPU-2bff57bc-de15-87c1-517c-4151c5132738
Jul 14 23:00:16 Hebegb kernel: [ 6891.806879] NVRM: Xid (PCI:0000:01:00): 32, Channel ID 00000000 intr 80040000
Jul 14 23:00:16 Hebegb kernel: [ 6891.808836] acpi LNXPOWER:13: Turning OFF
Jul 14 23:00:16 Hebegb kernel: [ 6891.808889] acpi LNXPOWER:12: Turning OFF
Jul 14 23:00:16 Hebegb kernel: [ 6891.808942] acpi LNXPOWER:11: Turning OFF
...