I have several types of data: Postgres, pure text, and media files (images, audio, videos).
I use Postgres on Railway for my projects, and I back them up using GitHub Actions. I keep two copies: one as an artifact, and the other on Hetzner Storage Box through Borg.
My pure text files are mostly stored on GitHub, such as my blog, TIL (Today I Learned), or diary. My diary is very important, so I also back it up to Hetzner Storage Box and another Git hosting provider—Codeberg.
The media files are stored locally, and I keep one copy on my portable hard drive.