Since this update (but I have applied the last two Stable Updates at once) locking the screen in KDE Plasma on X11 generates an error like this:
The screen locker is broken and unlocking is not possible anymore.
In order to unlock switch to a virtual terminal (e.g. Ctrl+Alt+F2), log in and execute the command:
loginctl unlock session 2Afterwards switch back to the running session
In Wayland, screen locking is fine. All the users on the machine share the same problem.