Just compiled 5.10.1 from source with the default config. Stuck at boot, log shows systemd fails to mount my XFS (multimedia) drive. Forcing to boot into default runlevel afterwards went fine. :-)

Just did a quick search and obviously beginning from 5.10 linux rejects to mount XFS versions older than V5 by default.

There's a config option that (re-)enables support for XFSv4 drives another couple of years.

I'm going to upgrade my media partition soon, but I wanted to leave a note here that XFS users might run into troubles.