This. I use Restic, the cloud service doesn't know about what I send, it's just encrypted blobs as far as it is concerned.

> encrypted blobs

I like how you can set multiple keys (much like LUKS) so that the key used by scheduled backups can be changed without messing with the key that I have memorized to restore with when disaster strikes.

It also means you can have multiple computers backing up (sequentially, not simultaneously) to the same repository, each with their own key.