Hello!
Do you hate the watermark preview banner?
Add the text HideDesktopPreviewBanner=true just after [] in the file ~/.config/kdeglobals. You will have something as the following:
[General]
HideDesktopPreviewBanner=true
Better for OLEDs displays, stylish, auto-suspend all-blacks displays, etc.
Just get a overlay that covers it up. Problem solved.
Seriously though, I though the solution was to cross it out for a second