Sorry. We’ve locked your account. The confirmation email we sent to ******** was returned and we’ve locked your account to protect your Firefox data

Hello 907c95,

That must be frustrating ....

Would you please take a look at this article and scroll down to :

" You have received a message that your account has been locked "

https://support.mozilla.org/en-US/kb/forum-response-firefox-sync-verification-email-faq

I have the same problem. The link only says to wait 24 hours which did not help. It’s been many months and still getting “Sorry. We’ve locked your account.”