SUMMARY
When one uses a copy-on-write filesystem like BTRFS or ZFS, it's oftentimes helpful to boot into an old snapshot of either your root or your home. However, KDE refuses to start on a read-only home, which makes it a hassle to boot into automated snapshots as generated by e.g. snapper.

STEPS TO REPRODUCE
1. Create a BTRFS subvolume for your home directory. Modify your fstab to have this newly created BTRFS subvolume mounted as /home, reboot, and log into plasma so that it creates all the needed files for a /home/<you> in that subvolume.
2. Create a read-only BTRFS snapshot of your home directory using snapper.
3. Modify your fstab to use that read-only snapshot as /home instead of the current one next time the computer is restarted.
4. Restart the computer.
5. Try to log in to plasma.

OBSERVED RESULT
Hangs in the splash screen.

EXPECTED RESULT
Should recognize that it's on a read-only snapshot, avoid writing to files like ~/.xsession-errors, start, and run as usual with the caveat that it's not supposed to modify any files.

SOFTWARE/OS VERSIONS
Operating System: Debian GNU/Linux 12
KDE Plasma Version: 5.27.2
KDE Frameworks Version: 5.103.0
Qt Version: 5.15.8
Kernel Version: 6.1.0-6-amd64 (64-bit)
Graphics Platform: X11
Processors: 20 × 12th Gen Intel® Core™ i7-12700H
Memory: 62.5 GiB of RAM
Graphics Processor: Mesa Intel® Graphics
Manufacturer: SLIMBOOK
Product Name: Executive

ADDITIONAL INFORMATION