@benjaminhollon It was spam that had gotten through. Sent from #Freshdesk (with DKIM passing so it's really from their systems), pretending to be Hetzner.

When I thought about it for a minute, it made no sense as I don't even pay for DNS on Hetzner, and I am my own registrar for that specific domain.

I made the good choice of ignoring the email until I had woken up fully, and didn't start "fixing" the situation directly on my phone in bed. Cooler heads prevail!