I Just installed OpenSuSE 15.2 on a Presario PC, 4GB, KDE Plasma.
Everything seems to work except "switch user".
I have two users and can login separately on each, no problem.

I click on "Lock Screen" and on the new screen I click
on "Switch User". Black screen results.

"Control-Alt-f7" will take be back to the previous session,
but if I try "Lock Screen" and "Switch User" again the mouse
is dead and everything hangs.

Thanks for a hint.

Also posted in OpenSuSE forums.

Could you please specify the exact Plasma version? There are so many different distributions out there, keeping track which version ships which Plasma version is almost impossible...

Quote from the OpenSuSE ~15.2 documents:
KDE
This release uses KDE’s Plasma 5.18 Long-Term-Support version.

Ah, kinfocenter told me
KDE Plasma Version: 5.18.5
KDE Frameworks Version: 5.71.0

Oh, interesting, I can confirm this, and I think this is definitely a bug. Since I don't normally switch users (and I guess most devs don't, either) this must have slipped from attention.

Could you please report this on https://bugs.kde.org/enter_bug.cgi?product=plasmashell for the component "Lock/Logout" and give the bug number here so I can confirm this, as I use the same version.

OK, entered as https://bugs.kde.org/show_bug.cgi?id=424322

Thank you, trying to get a backtrace, but the computer completely crashes, can't even access a shell anymore