KDE - changing the way you use Qubes

[KarlinQubes]

Installing and running KDE as Desktop Environment

Don’t do this. (Besides the fact that dnf wont do anything in dom0, so it just wont work.) Because of the refactoring in 4.1, you get KDE with Qubes support by issuing sudo qubes-dom0-update kde-settings-qubes in dom0. Some rough edges, but all the benefits of KDE and decent coloring.

Try what unman said here