For these and other feature parity issues, see New Teams desktop client: Known issues. You should remain with the classic app if you're using call queues, delegations, or the Avatar app, or if you rely heavily on speed dial.
If you cannot activate the new Teams on your managed computer, ask your IT Pro to contact the Endpoint Management team to manage this policy for you. You can move freely between the new and old versions of Teams, as long as you're not in an active meeting. This client has many new features and is built on a completely different engine, which promises significant CPU and memory performance improvements.
Starting in late September 2023, some Microsoft Teams users at Indiana University may begin to see a slider bar at the top of their Teams client to try the 'New Teams'.