CleanCache was off, so nothing ever pruned /var/cache/pacman/pkg - 23 GB on the
machine this was found on, with three 3.2 GB copies of one package. Trimming
only drops older versions of installed packages and cached versions of
uninstalled ones, so the cost is downgrade depth, not working software.
flatpak uninstall --unused moves from CleanCache to RemoveOrphans, where it
belongs: unused runtimes are the Flatpak equivalent of orphaned packages, and
removing installed software should not hide behind a flag named for cache
trimming. RemoveOrphans stays off - 'orphaned' only means nothing depends on
it, which is also true of something installed deliberately.
The log now reports what a trim reclaimed, since a real paccache run says
almost nothing and there was otherwise no way to tell it was working.