I suspect this is the issue discussed here: All KDE apps crash upon opening / interacting - #2 by pg-tips
It’s a problem with the latest version of qt6-qtwayland deployed in Fedora.
If you updated today, then you most likely have version 6.9.1-2 of that package installed, so you could try downgrading to 6.9.1-1 as per 2375356 – qt6-qtwayland 6.9.1-2 breaks KDE Plasma lockscreen, requiring user to drop to TTY to unlock session
The “…/osd” error message is unrelated I think. I also see this message on a system which has never had the bad version of qt6-qtwayland installed, and never had the broken lockscreen.
The timing of the updates has meant that many users got their qt6-qtwayland upgraded at the same time as the Plasma 6.4.1 upgrade. So this issue is often being attributed to Plasma 6.4.1, when the cause is actually this Fedora-specific qtwayland package.