I had this exact same thing happen to me a while back. Luckily the account was one I had created just for this one user group who required I become part of their AD domain to access MS Teams. I tried getting back into the account and hit the same roadblock this guy did. I didn't care that much and just abandoned the account.

I figured it was something that Microsoft would soon fix, as it was such an obvious cluster; I'm surprised the issue still exists.