mplayer is (finally) in bookworm: Bug 1005899 is fixed. [2023-02-13] mplayer 2:1.5+svn38408-1 MIGRATED to testing https://tracker.debian.org/news/1420921/mplayer-215svn38408-1-migrated-to-testing/
So Bug#1018747 is fixed and gimp-gap can be returned to bookworm
