10/7/2020, 5:00 PM, RESOLVED: Microsoft reports that all services are now working normally. They traced the issue to a network congestion problem in their cloud infrastructure.
10/7/2020, 2:20 PM, UPDATE: Microsoft reports that Teams, OneDrive, and SharePoint services are healthy, but some individuals may still encounter issues with Exchange Online (Outlook) related services.
10/7/2020, 12:30 PM: Microsoft reports that users may encounter issues accessing or using features in Microsoft Teams, Exchange Online (Outlook), and SharePoint Online/OneDrive for Business. So far reports to the Help Desk have mostly reported issues with Teams chat, status/presence indicators, and possibly Teams Voice. Microsoft is investigating the issue.