If they receive any kind of abuse report, they instantly put you on a 24h timer, but they won't show you contents of that message. If you do not respond in time, they will simply block the IP. What's strange is that I was using Cloudflare in front of Hetzner, but it seems that Cloudflare is ratting their users out and forwarding any abuse mail to the owners of "cloud protected" IPs, all without any notification or warning. Hetzner then sends you an email like "Please remove <sitename> from our network within the next 24 hours. This site violates 6.2 of Hetzner's terms and conditions.", where site in question is an obvious mirror/search engine of another social network.
What's perhaps more irritating is that Hetzner Cloud has a tiny LIFO queue of ipv4 addresses unique per customer, so you will get the same IP as soon as you release one. You can imagine what happens to a Rancher-managed k8s cluster with Hetzner node driver when one of those IPs gets a no-route: it will get stuck trying to re-deploy a failed node. Mine eventually fell apart though because I did not attend to it for a couple of years.
I'm now hosting from a proverbial garage (NixOS and cron) but proxying traffic through a cheap cloud VM, which saves me at least $1500/mo.