Microsoft has reiterated that support for Internet Explorer (IE) connections to Office 365 will end the next day ("Teams" has already ended support for connections).
After this date, you will not be able to connect to Office 365 using IE / new features will not be available / you will be able to connect but problems will occur.
If you are currently using Office 365 from IE, please connect from another browser (Edge, Google Chrome, etc.) in the future.
[End of support date]
August 17, 2021 End of connection support for Outlook, OneDrive, etc.