badboybackagain I'm currently using Oracle Cloud. They offer a very generous free tier with some storage space for free. You can spin up a small VM (free too) and use it exclusively for the backup role.
I'm also using Hetzner for the other roles and there you can create a small machine (they start very cheap) and also the block storage is not very expensive, you can start with a few Gb (depending on your data) and grow from there. They allow you to expand your block storage, and also rescale your machines if you need more power.