Steps to reproduce: 1) Wait for KDE to lock screen, display password prompt etc 2) When KDE lockscreen is up, move your mouse pointer Expected results: mouse moves Real results: Instead of mouse movement, KDM is instantly killed & desktop reveals without entering user information I have this issue reproducible on latest Kubuntu release & debian unstable out-of-box. Reproducible: Always This is very annoying behavior that forces me to lock my screen using external screenlocker. This is a security breakage & feature non-working as I see.
I have something similar in mine Debian unstable. Sometimes instead of asking password it kills screen locker and reveal plasma desktop. But it is buggy desktop: it doesn't respond on keyboard or mouse clicks, doesn't show on hover effects but mouse is movable. Only cure is to kill plasma-desktop process. I don't think that it is reproducable always
That's not a bug, but a feature: grace time. This is configurable and can also be disabled. The idea is to not require password if you are sitting idle in front of the screen.