Similar: Group Policy keeps reverting on Windows 5] Check the Prevent changing desktop background setting Suppose you cannot change wallpaper in Windows 10 in any way.

To change the background we needed to open a windows explorer window and navigate to the desktop folder. From there we could right click in that folder only and change the background.

Windows 11 desktop background keeps changing? If Wallpaper changes automatically after a restart, maybe Slideshow.ini & TranscodedWallpaper files have got corrupted.