This is what happened. I saw /usr/share/endeavouros/backgrounds/endeavouros-wallpaper.png vanish the moment I changed the setting. I don’t plan on reinstalling the OS again on the Steam Deck because it is really annoying and got it mostly working (if you are interested in my progress I made this thread in the newbie sub-forum Setting up EndeavourOS on Valve Steam Deck)
I think someone should test this out on a VM to verify I somehow have a faulty installation media or something crazy. This is how I specifically recreated it.
- Default language, timezone, and keyboard layout.
- KDE Plasma as the Desktop,
- Grub as the bootloader.
- Uncheck Firefox from the preinstalled packages (If your wondering why it’s because I use Librewolf, no need to have Firefox installed along side it)
- Completely wipe the disk, format the disk as ext4, swap to file.
- Obviously leave automatically login on startup off.
- Use a separate password for root.
Then once the system reboots into the fresh OS monitor /usr/share/endeavouros/backgrounds/endeavouros-wallpaper.png and then go to System Settings>Startup and Shutdown>Login Screen (SDDM)>Behavior>Automatically log in as user (into a Plasma X11 session).