The author uses Restic + Backblaze B2 storage. I was recently setting up backups for my homebase as well, and went with Restic + BorgBase [0]. Not affiliated, just wanted to share that I think they have a nice service with a straight-forward pricing model. They are the company behind excellent Pikapods [1], which may be interesting to the homelab crowd.
I also use backrest/restic on my NAS, but I went with a Hetzner StorageBox instead, a little cheaper for 1TB (I pay 5USD monthly including VAT, billed monthly too).