As interesting as this discussion has been, I want to point out that we have no proof of any of this.
- The link says "my friend got this", so even the person who authored that post isn't claiming to have received this notice. This is a second hand report, at best. For all we know, their friend received this notice years ago, and mentioned it to the OP, who didn't realize it was old news.
- We don't even have a screenshot of an email like this (which could also be easily faked, but it would be more credible than that zero-effort text post), nor do we have any public statement from Hetzner.
- It's not like a flood of people are reporting this happening to them... I haven't seen a single person in this HN discussion mention receiving a similar notice from Hetzner. I didn't read the entire thread that was linked, but I also didn't see anyone there claiming to have personally received this notice either.
- The phrase "we’re writing to you today because of your traffic use" does not appear on any google results other than the linked thread, so this could be the first and only time that Hetzner has reached out to anyone about this, if it is even real, and even then... they might be motivated to cancel their contract with the customer for real reasons that they don't want to discuss with the customer, in hopes of lessening the drama. Companies do that sometimes, as crappy as it may be, so this whole thing could be a red herring if it only happens to one account.
If anyone does have additional evidence or anecdotes to contribute related to Hetzner getting upset at "unlimited" traffic usage, that would be nice to see. If this is a pattern that can be confirmed, then all of this discussion is absolutely warranted.
Hetzner might have sent this notice, but I've seen people get similarly flustered about other things on the internet that turned out to be fake. Can we gather some more evidence before raising our pitchforks? Literally anyone could have made up a story like this about any company, and people do make stories like this up.
Those are just my thoughts, but now that everyone has their pitchforks out, I doubt they are willing to provide benefit of the doubt to the accused party and wait for more evidence to show up.