Halfway through the installation it throws me back to the login screen. When I try to continue the update/upgrade it does it again.
I already did a rollback with snapper and forgot to note at which package it exactly happened.
So anyone trying to update, beware that the update might not get through.
I'll wait a week and then try again.
Update
Ashged on reddit:
*Yeah, unfortunately the update doesn't work within KDE. No idea if/when they'll make a fix for that.
The update however works outside KDE, in an IceWM desktop or a TTY. For best results, first log out of KDE, then using Ctr+Alt+F1 go a text based enviroment. Log in there, use sudo zypper dup, then after it finishes, reboot and log in to your regular KDE desktop. Plasma 6 should upgrade succesfully.*
I followed Ashged's guide to install the update and upgrade to KDE6. It worked and now let's see if I run into any bugs. So far everything seems to work fine.