Disclaimer
Flatpak uses OSTree, like Fedora Atomic Desktops (Silverblue, Kinoite etc) and similar to BTRFS snapshots.
So many files are deduplicated and linked, not actually there
https://gitlab.com/TheEvilSkeleton/flatpak-dedup-checker
50GB without
31GB with deduplication
21,4GB with BTRFS compression
A lot of that data doesn’t actually exist, ostree hardlinks data blobs internally, so the actual size on disk is much smaller than most disk usage tools will show.
Thanks! The same goes for ostree system versions and BTRFS snapshots probably.
I have a similar problem with virt-manager and I think that doesnt create dynamically allocated qcow2 containers?