My current setup includes two 1440p monitors and a 4K TV . In the evening I use a script to switch off the monitors and use the TV. Due to the different resolutions, scaling is a problem. Both X11 and Wayland have their own problems....
Don’t really have an Idea, but to add to your problem…
I have a 4K TV and 2 1080p Monitors and switching beneath them. Using NVIDIA graphics card with up to date drivers. All I can say, I’ve tried using KDE multiple times now, but always ended up getting weird Bugs, Micro stutter, etc on my 4K TV with KDE. So I always reverted Back to Cinnamon, GNOME, etc, because there it is working fine.
Wayland/X11 problems with 4K HDMI TV
My current setup includes two 1440p monitors and a 4K TV . In the evening I use a script to switch off the monitors and use the TV. Due to the different resolutions, scaling is a problem. Both X11 and Wayland have their own problems....