Microsoft is addressing a problem affecting Microsoft 365, Exchange Online, and Microsoft Teams, with outage issues reported by around 5,000 users on Monday morning. The company is investigating issues with accessing Exchange Online and Microsoft Teams calendar functionality. Users may also be experiencing problems with Word, Outlook, and Excel, which are part of Microsoft 365.
Source: https://www.whio.com/news/local/microsoft-working-fix-nation-wide-outages/N6DK7W3NRBG3LALQN4L44MFLEA/