Do you get that error if you try using a different account (non-MDM, for example a personal Gmail account) after a factory reset, never using* the MDM account post-reset?
* Feel free to use it in a third party browser such as Firefox or Brave, as another commenter suggested. Just don't use it for an OS login.
* Feel free to use it in a third party browser such as Firefox or Brave, as another commenter suggested. Just don't use it for an OS login.