Microsoft Teams Chat feature is based on Microsoft Teams desktop client and Microsoft is extending Teams capability by bringing the dedicated button right to your taskbar. Microsoft is planning to enable advanced features like audio and video calls, meetings, screen sharing and other capabilities. Users can only sign in, add contacts, and connect via individual and group chats. You can simply tap on the Chat icon in the Taskbar to reach out to your contacts. You ll see your most recent individual. and be able to respond or start a new chat or call.
Source: https://www.bleepingcomputer.com/news/microsoft/microsoft-teams-chat-feature-rolling-out-to-windows-11/