Indeed, that's just for the rooms where users are joined. But be aware that if you join a large room on matrix.org from your own homeserver, it might fill-up yo

Indeed, that's just for the rooms where users are joined. But be aware that if you join a large room on matrix.org from your own homeserver, it might fill-up your disks with a lot of old state (and that might take large amounts of CPU+RAM for days, too).