Just run it on Hetzner. You get 20TB egress monthly per server, which should cover a lot of DDOS activity.

You could also probably create a script to run on another machine that uses the Hetzner (or other cloud provider) API to monitor usage and shut off your server if it exceeds usage limits.

It was running on Hetzner, but I did not like the idea of having to rely on some script to try to avoid a disaster as opposed to just be able to set a limit (that they do not support?).

* Even if the risk is obviously very low, the value of running my gemlog isn't great. Not really worth any non-zero risk of significant costs.