It happened to me too, and I was unable to verify myself by any acceptable means due to being based in a country other than that of my passport. Having been redirected somewhere else for the identity verification onboarding, I think the process is outsourced by Hetzner to a firm of security specialists apparently oblivious to edge cases. Nice work if you can get it.

There's some other specific character besides spaces that's also not permitted in passwords. It's a normal printable ascii character but I can't remember what it is any more, and sometimes it's not caught. Let's hope nobody signs up with it by mistake.