I had backblaze, and it’s really a bummer they don’t support linux. The closest one I’ve found is Icedrive, but it costs a bit more. I don’t mind paying a bit more though for a FOSS solution (technially not free but yeah). I probably only have 2 TB of actual important stuff but it would be nice to have more for future.
seconding this; unless you’re paying for it: they use your data to make money and have (and do) make use of your data as leverage to get you to pay more.
setting up your own home server that’s accessible to the internet is much cheaper, but it does come with risks that you must make yourself aware of to mitigate.
I’ll add that if you do use cloud storage (a.k.a. someone else’s computer) for backups, make sure all your data is encrypted (preferably also compressed and deduplicated). If you value your data you’ll also keep a separate, offline copy.