Can’t change wallpaper/backgrounds
With the latest Cinnamon Desktop update to 5.8.4, an issue with the Background Settings emerged, where thumbnails will not show up in the settings panel.
The issue has been fixed and now we just have to wait for the fix to be pushed out. Fix 11746
In the meantime, you can change the backgrounds using Nemo file manager, just open Nemo and navigate to /
usr/share/backgrounds/delinuxco , right click on the image you would like to use on the Desktop and “Set as Wallpaper”