Wallpaper links that name a missing JPEG or PNG point at WebP in a merged migration
Pull request 14603 merges a migration that points a wallpaper choice at the WebP file when the old JPEG or PNG is gone. A dangling link had left a black background. The merge is not in version 4.0.4.
The pull request says bundled JPG and PNG wallpapers moved to WebP, and a theme refresh kept the selected file on purpose. The current background, and the remembered file for another theme, could still name an image that was gone. The shell opened that missing file and showed black.
The migration changes a .jpg, .jpeg, or .png choice only when that file is missing from the named theme and the WebP replacement is there. Another extension, or a broken path with no matching WebP, is left alone. manuaudio opened the pull request, and emirb merged it. The pull request says the author did not repeat a full upgrade from stable to edge. The test used the file layout from the report.