Known issues and solutionsに書いてあるよ。

https://forum.manjaro.org/t/stable-update-2024-10-01-kernels-plasma-6-1-5-kde-gear-24-08-1-libreoffice-virtualbox-7-1/168682/2


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 56