I get “shutdown failed with the exit code 1” on shutdown and restarts.
Also, my screen frequently starts flickering on boot. I have a nvidia GTX 1650 and am running linux58.
But the system shuts down, does reboot properly?
I usually recommend this, but of course adapted to your Monitor and connector + the kwin.sh part, and ONLY if we talk about a Desktop PC
You could also try this
Otherwise we would need more information from you, as described here:
It reboots with the error message but it still boots.