borg backup with rsync.net
Borg does de-duplication and compression, I've used it for multiple things like backing up minecraft servers and it can reduce the final backup size by a lot (like 1-2 TBs to a hundred of GB, though that was with content that was highly compressible and didn't change much over-time so the deduplication did a lot too).
There is also borgbase.com which looks a bit better and focuses only on borg repositories instead of also being compatible with just about any usual tools (eg rsync, rclone etc)