root cause
extra "Outlook.com functionality such as Calendar APIs consumed by other services such as Microsoft Teams are also affected."
Is this parenthetical, or is this what caused the outage? It seems suspiciously detailed when they are still investigating. Anyway we can certainly expect plenty of Teams-related outages as that bag of poo gets more integrated with 365-Office/Microsoft/Whatever they are calling it lately.
Biting the hand that feeds IT
