I used AWS for a bit and then stopped, and then forgot about it. I've kept my Amazon account up to date, but not my AWS details. For years I continued to use my Amazon account without ever needing to use the MFA, so forgot I ever activated it. This year they've suddenly decided to enforce the MFA globally. I blame myself for not removing the MFA when I closed the account, but you can hopefully see why it's a frustrating user experience also. And like I say, the net result is a less secure Amazon account for everything but AWS until I can remove the MFA requirement.
Re notarizing, my understanding is that I need to use a US notary service for it to be valid for a US document (eg available via the US embassy).