Teams does not support window.open. Because lack of window.open, OAuth card fail.

Teams provide another solution called "authentication flow for tabs". They allow tabs to "connect to OAuth" without window.open.

We should study how it works and see how it would fit in Web Chat OAuthCard or other SSO story.

https://docs.microsoft.com/en-us/microsoftteams/platform/concepts/authentication/auth-flow-tab