Beginning November 30, 2020, the Microsoft Teams web app will no longer support Internet Explorer (IE) 11.
IE 11 has been available since 2013 when the online environment was much less sophisticated than the landscape today.
We recommend that you update to the new Microsoft Edge for a safer and more innovative online experience. It lets you standardize on one browser and seamlessly experience the best of the modern web in one tab while accessing a business-critical legacy IE 11 app in another tab.
This article has more information about Microsoft Edge https://www.microsoft.com/edge?form=MY01BL&OCID=MY01BL
There is also more information in this blog in Englishhttps://techcommunity.microsoft.com/t5/microsoft-365-blog/microsoft-365-apps-say-farewell-to-internet-explorer-11-and/ba-p/1591666