I can add that to options.rst, but the terse explanation still seems pretty meaningless; at least for me there’s no visible difference when I run nextcloud with --background compared to running without.

This could be due to #2333 though, if running without --background is supposed to open the main dialog (which has never worked on Focal). If so, I’d mention this too, something like: ”Launch the application in the background (without opening the main dialog).”