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
Thanks!
50GB without 31GB with deduplication 21,4GB with BTRFS compression
And I have to say I have many apps. Not as many anymore, and no EOL runtimes apart Onionshare anymore.