@timmeh Your assessment is correct. If you switched the backups to rsync mode, you can remove the .tar.gz files. They are left overs from your previous backup. Maybe we can add an option to remove the old backup files (of previous configs). But of course, that will require cloudron to remember previous config as well.
Also, to be 100% clear, only remove the .tar.gz files. Do not remove any other files in the snapshot directory. The snapshot directory is the "working directory" of the backup system and stores the previous state.