iso-profiles-settings/tromjaro/gnome/desktop-overlay/etc/skel/.config/gnome-control-center/backgrounds/last-edited.xml

<?xml version="1.0"?>
<!DOCTYPE wallpapers SYSTEM "gnome-wp-list.dtd">
<wallpapers>
  <wallpaper>
    <name>Current background</name>
  </wallpaper>
</wallpapers>