https://www.bleepingcomputer.com/news/microsoft/microsoft-fixes-issue-blocking-microsoft-teams-outlook-logins/

Microsoft has fixed a known issue causing Microsoft 365 to experience authentication issues when logging into desktop client apps like Microsoft Teams, OneDrive for Business, and Microsoft Outlook.

When attempting to sign in, users are shown a message saying, "We ran into a problem. Reconnecting…" and asking them to restart the application.