The SEP (Symantec Endpoint Security) or SES (Symantec Endpoint Security) Agent may interfere with the Microsoft Teams app, and it can prevent the application from starting correctly.
To prevent SEP/SES from interfere with Microsoft Teams, Add the following Exclusions
Wild card (*) is not supported. We recommend to use the Prefix variable [USER_PROFILE] which will correspond to all the users.
Configuring Exceptions policies in Endpoint Protection Manager
How to include or exclude Teams from antivirus or DLP applications