The background and the lock screen are drawn by Quickshell, so they decode
through Qt, which ships handlers for png, jpeg and gif but not webp. Any
third-party theme shipping a .webp background comes up blank without the
qt6-imageformats plugin, and extra themes are their own repositories.
Only the dependency is taken here. The background conversion that came with
it re-encodes all 79 bundled backgrounds, which 4.0.1 has no need of.
(cherry picked from commit a4219f8fbeb85ee7a2bc0e14eda9d38cc85d3d0d, dependency only)
David Heinemeier Hansson
9e79b24342