I ran some small tests and found the culprit. The culprit is BackBlaze (I'm not sure if it has other APIs), but I've switched to Wasabi S3 and not only are the backups being transferred much faster, but there are no memory issues. My 3-day backups now only occupy 52GB, whereas with BackBlaze it was over 300GB. I also tested Enhance incremental backups, which work great, but in my case, it's not very secure because I would need to store backups on another server, which I don't have. I have a VPS server, and I think now with Wasabi, backups are done correctly and quickly without drawbacks for small cases. For larger servers, Enhance incremental backups are definitely a better choice. In my case, Wasabi S3 is much faster than BackBlaze.
