Unreliable login - black screen

[Kobold]

Its probably this here, newly introduced KDE bug:

@philm

KDE Plasma hangs on Shutdown, Restart and Logout

With KDE Plasma 6.1, the session saving feature can make Plasma hang.
A workaround is to disable it in System settings > Session > Desktop Session, by choosing “Start with an empty session”.

• KDE Hangs on Shutdown, Restart and Logout. Black screen [SOLVED] / Applications & Desktop Environments / Arch Linux Forums