Just for information: a cosmetic bug. i do not really need to change username or password fields. as this bug is still not fixed i post it here. I am not sure which package is the culprit. i doubt it is xscreensaver itself, it is some dependency for sure in my point of view.

i use i3wm with xscreensaver

when i lock my screen with xscreensaver the user interface is broken.

it does not show the login name and password fields anymore. Instead the fields are shortened without text to the bare minimum of a few milimeters

unlocking works of course. i think an update ~1-2 weeks ago broke it.

Which distro/version is this on?

Have you tried looking in the log files for some indication of an anomaly at the time you lock/unlock the computer? I'm not sure which log file to look in, but I'd start with /var/log/system or /var/log/Xorg.0.log (or their equivalents).

If you have another DE/WM installed, you might try switching to is and seeing whether you can replicate the problem.