I was prompted for GitHub credentials (which never happens), entered them
Did you enter a personal access token or your password? If you used your password, can you try with a token?
and got an error. I was still able to do the push through another client without a problem.
Hmm one possibility is that you use SSH instead of HTTPS in the other client? If you use SSH, it doesn’t matter if you have 2FA enabled or not. If you use HTTPS and have 2FA enabled, you have to use a personal access token.