I'd never heard of VPSs prohibiting any specific use case; I have 3 restic repos on my VPS and have had them for close to 6 years now (well, borg until early this year, now restic, but it's the same principle).
I've looked through all the server types in https://www.hetzner.com/legal/system-policies (my VPS provider) and I can't find anything about not using for data backup.
(They only prohibit: crypto mining, IP address scanning, changing the MAC address, and using fake source IPs.)