Privacy from the vendor, for cloud backups, is barely addressed by most of the cloud storage providers. I find the best solution is to - like many comments here about photo and music storage - stick to older more stable standards that aren't about trying to sell you services.
In my case that means a chunk of SFTP-based storage, and rclone to make that storage encrypted at-rest.
In my case that means a chunk of SFTP-based storage, and rclone to make that storage encrypted at-rest.