Backblaze personal backup used to only keep files for 30 days from your last activity, although I see they now let you keep old files for a year, for an extra $2/month.
Personally, I use Arq Backup and Backblaze B2 (their “real” cloud storage). Arq is a one-time paid app that does differential encrypted backups to your choice of local storage or cloud provider.
Keeping 1TB of backups cost me around $5 per month, and the files won’t disappear on me if my computer stops working for a month.