Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Thanks RositaKP, I appreciate your answer. I suspect your iPhone might have updated itself despite your settings. I have experienced that before.
You will generally experience a more stable and secure iOS if you update to 14.2, but it will unfortunately not solve your mail issue.
My best guess is that iOS 14 has introduced an OAuth interoperability issue between the Apple Mail App and the Microsoft outlook.com mail servers. It may take a while to solve.
I will temporarily use the Outlook App until Apple/Microsoft get this issue sorted out. The Outlook App has notifications etc.