As per @jonp’s suspicion over the HDMI expansion card, I removed my HDMI expansion card (slot 4), booted my system (secure boot, luks, fedora 39), logged in, opened a couple of apps and then closed the lid for two hours, all on battery power, starting the test at ~60%
| Left-hand side expansion cards |
Right-hand side expansion cards |
| 1. USB-C |
3. USB-C |
| 2. USB-A |
4. Empty (used to be HDMI) |
Upon opening the lid, the screen was blank (backlight on) for ~70 seconds before I was presented with the login screen. I logged in and a couple of GUI applications had errors. Battery was far from empty (somewhere above 40%). I attempted to open a terminal twice to do a write test with $ touch as I didn’t already have a terminal open, but gnome-terminal failed to open both times.
I then pressed ctrl, alt, F3 to move from my graphical gnome session to tty3. About 4 error messages appeared (can’t remember exactly what they were about, I believe something about btrfs?) and was then on a blank screen with a single blinking underscore in the top left for a few seconds, before these errors began being printed to the screen:
TLDR: A 2 hour suspend with no HDMI expansion card still resulted in a read-only system after waking (which took 70 seconds).
Perhaps relevant, as my framework used to be Intel, I’m using 2022 expansion cards which came with my original Intel framework, now plugged into an AMD motherboard.
I’m going to try disabling secure boot next, whilst keeping the suspect HDMI expansion card disconnected.
EDIT: After removing the kernel arguments module_blacklist=hid_sensor_hub and nvme.noacpi=1, my system has been waking from suspend immediately with no read-only problems 
Will post again after longer term testing where I plan to slowly re-enable secure boot and reinstall the HDMI expansion card if all goes well.
.