This thread is not really interesting because we don’t have the Hetzner’s side of the story.
The lack of response from Hetzner is part of what does make it interesting.
Adverse inferance. The company thinks it's better for them to keep quiet than to tell their side. That speaks volumes.
I agree and don't think you should be downvoted for this opinion. With only one side of the story it's impossible to draw any conclusions yet.
Of course there is usually a bit of a chicken and egg issue with this sort of thing. Many companies only respond at all when complaints go viral on sites such as hn.
And now we do have Hetzner replying here (and on reddit), and it sounds like they did indeed communicate the termination well in advance (but for whatever reason the OP didn't notice it at the time).
None of this is to say that Hetzner responded in an ideal manner, and whatever reasons exist for the termination are still not known, but it seems likely at least some of the OP's criticisms of the process are not valid.
Of course now it's too late as many will never come back to review this thread. As often happens on hn when somebody complains about something, the pitchforks come out before there is enough information to really understand the situation fully.
My rule of thumb is "if you had the opportunity to tell your side of the story but chose not to, then I'm going to accept the other party's side of the story as gospel".