My monitors default resolution is 3840x2160, but when I let KDE use this any screen I startup just is a black square and some times KDE is just a black screen. I have set KDE to 1920x1080 and config.txt to 1920x1080, but SDDM and the greeter refuse to acknowledge this resolution as Xorg scans all of the modelines for my monitor and settles on the 3840.
First, this is on a Raspberry Pi 4B and Xorg recognizes the 1920x1080, but the TV’s default resolution is 3840x2160 and X and/or KDE has a problem drawing the items on the screen at this high of a resolution. What happens is some boots the scrren is completely black with only the mouse rendering and other times KDE comes up, but system settings, dolphin, kate are black if I try to maximize or enlarge the screen any amount.