For quite some time now, KDE has intermittently been unable to go to sleep. It will either go to a black screen with the cursor still showing, and the computer running, or it will show a half frozen sddm looking screen with the computer still running. The computer, in both cases, will be wholly unresponsive, and the only way to get out of it is to forcefully shutdown the PC by, for example, holding the power button.
I had the same issue running fedora kinoite on an old laptop with integrated Radeon graphics. Scrambled video when waking from suspend, and even if it does start to look normal its still pretty much frozen.