The new version of Teams is now available for users to launch. The main changes consist in greater optimization of the application launch speed, meetings, chats, as well as in lower hardware requirements. The new version is also more flexible with the ability to log in across all tenants, allowing you to receive notifications from all tenants, regardless of which one is currently in use.
The classic version of Teams can continue to be used until March 31, 2024. If users continue to use classic Teams, they will be automatically upgraded to the new Teams in the coming months.
Minimum system requirements for new Teams: Windows 10 Vibranium (20H1) 10.0.19041 and Microsoft Teams (work or school) version 1.5.00.29212 or higher. The new Teams for Web meets the same browser requirements as classic Teams for Microsoft Edge and Chrome browsers.
https://support.microsoft.com/en-gb/office/switch-to-the-new-microsoft-teams-2d4a0c96-fa52-43f8-a006-4bfbc62cf6c5