If you use the Microsoft Teams application, you may receive a message stating that the “Classic Teams” will soon be unavailable.
Beginning Monday, April 1st, Microsoft will be automatically upgrading the Teams application to “New” Teams. New Microsoft Teams has been rebuilt from the ground up for a faster, lighter, more efficient, and flexible experience. The client has also simplified and streamlined joining meetings and interacting with chats and channel messages. Much of the New Teams’ interface will look familiar; learn more about New Teams here: https://support.microsoft.com/en-us/teams
There’s no action needed on your part, this upgrade will happen automatically.