https://www.bleepingcomputer.com/news/microsoft/microsoft-365-authentication-outage-users-unable-to-login/

Microsoft 365 is experiencing a multi-factor authentication (MFA) outage that blocks users from accessing multiple Microsoft 365 services such as Office 365 and Azure according to user reports.

"Users may not receive authentication requests via phone call, SMS or within their authenticator app," says Microsoft on the Microsoft 365 Service health status page. "This issue could potentially affect any of your users if they are routed through the affected infrastructure."