I have the same issue. It used to work. I was trying to log in to diagnose why Supervisor seems to be unable to update to the latest ESPHome.
$ ssh ha
Welcome to Home Assistant OS.
Use `ha` to access the Home Assistant CLI.
# login
Shared connection to homeassistant.[my internal domain name] closed.
I haven’t changed any of my ssh keys. Ssh is configured to login to ha as root, port 22222, on the correct hostname, using my default key.