My personal issue is solved, indeed. But, just to make it clear, the issue is not solved, right?
My personal issue required two steps for solution: first, Henrik (@hmitsch) had to pull some levers to reset my profile login mechanisms or something like that; but I also had to perform some very risky and tricky operations with one hand to turn off the problematic autologin thing, as instructed by Henrik: “What you can do is clear the autologin method from localStorage, by running localStorage.removeItem(‘nlx-last-used-connection’) in the Console of your browser Developer Tools. This needs to happen while on the auth.mozilla.auth0.com domain, so best stop page loading as soon as you get to that page”.
So he did his part, I did mine, and I am clear, as I can now login using a Google account. But everyone else is still behind.
This error message [https:/uploads/mozilla/original/3X/c/5/c52a3496936c123e4a029d821ff570e422214375.png] should also contain (1) instructions on how to work around it and (2) a button for users to self reset their profile’s login (as it is needed to achieve the workaround). And this should not wait until “the end of the year”.
(BTW, there are other people not wanting mandatory 2FA that already managed to eventually get to this forum and say it: [IMPORTANT] Changing the look of your login - #16 by loureiro.rg, Can't log in to Mozillians - #5 by kang, etc.)
But, as for my personal issue, this topic can be closed.