I think this may be due to the recent 25.11 updates, but I'm not entirely sure.
sshd started to create forwarded agents under $HOME. This broke Josh since as home was /var/empty, so forwarding was impossible, resulting in this error:
debug1: Requesting authentication agent forwarding.
... 8< -- snip -- 8< ...
debug1: Remote: Agent forwarding disabled: couldn't create listener socket
Creating a home for Josh fixes this
manually merged due to tangled error