Also everything forbidden by German law results in a cancellation. So if you would have for example posted something before 2017 about a state leader that might seem like an insult your server might be gone. ( https://www.loc.gov/item/global-legal-monitor/2017-07-26/ger... )
https://cdn.hetzner.com/assets/Uploads/downloads/AGB-en.pdf Section 8.3
I'm awaiting donwvotes, but honestly, if they don't give you a reason, everything can be one, and refusing a service on arbitrary grounds seems illegal to me :D