Comment # 2 on bug 1120844 from Wolfgang Bauer

It may be related to bug#1120391 which mentions "a few tty-related fix patches"
in the kernel, though that is for Leap 15.0 and I have no idea whether
Tumbleweed is/was affected by it as well.

I don't think Plasma really has anything to do with VT switching though.
So probably a kernel bug anyway... (or related to Wayland?)