Error message "Your email was just returned. Mistyped email?" is shown on my new PC.
My new PC is showing the error message "Your email was just returned. Mistyped email?" when inputting the authentication code for Firefox sync login.
When I enter incorrect email/PW info I cannot progress to this stage. When I enter an incorrect authentication code I get a standard error code ("two-step authentication code required").
I recently reactivated an old PC a few days ago and used Firefox sync with that device without issue.