Having the same issues, I was attempting to join a second pve server to my new cluster, it prompted that I needed to remove tfa in order to authenticate for the cluster join, I went through the GUI to the TFA section and deleted both for my non root admin user, and my root user. After deleting that, I am unable to login to the web gui at all with any account. I am still able to access via root on SSH, and have tried to use the tfa removal commands, but I still get the same error on the GUI. Not sure what else to try at this point.
