When you archive a project, the UI gives the impression that the clips are supposed to go into clip category directories, e.g. Video clips, Audio clips, Image clips. The project file itself suggests similar with directories like videos, sounds, images. However, all the clips are actually stored within a single directory, the only one created, images. It doesn't seem to always be images, just whichever comes first alphabetically (lumas for a different project). Maybe there's no need to say Video clips, just videos, then it would be consistent all the way through?
Fixed by Commit 17d0ce55 ('Fix archiving' in the announcement for 21.12.1) I'm going to go ahead and close this, not sure of your convention, please undo if that isn't the right thing to do.