Last week, a major Azure Active Directory authentication issue affected users worldwide. A follow-up Exchange/Outlook issue later in the week affected European and Indian Office 365/Microsoft 365 customers. This week, Microsoft’s cloud services issues are continuing, affecting a number of Exchange, Outlook, Teams and SharePoint users.
In summary of full article found here:
Microsoft continues to point at infrastructure changes being the cause of the disruptions of service.
Preliminary Root Cause: A change was made to an internal service that controls routing across the Azure Wide Area Network (WAN). A bug in the new version of the service caused traffic to route non-optimally across the WAN, causing network congestion and packet loss.
Whether all of the recent disruptions are interconnected is still uncertain.