Difficult to reproduce, can be when we lock the session, close the macbook, plug a second screen and re-open. Or in another order. Personally I remember not having the focus on the password input by opening my MacBook onetime, I often plug and unplug screens
I was in a huge lecture hall and the presentation from the head of school was going to talk. He plugged in, turned to look at the display from the projector and it hadn’t come up yet. He types in his username and password and stood there waiting. When the projector came to life he had typed it all into the username field.
He fixed it up then displayed his desktop to us with all the pending final exam papers sitting there. No one in the hall showed any obvious sign of realising what had just occurred.