Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
It sounds like MFA is now being required for your admin account, even if no one remembers setting it up. If you're the global admin, try signing in from a web browser and see if you can reset or update your security info. If you can't get past the verification step, you'll likely need to contact Microsoft Support to recover access or have the MFA reset.