@ErikVet  Adding a website to a tab and creating an app that contains a custom tab are two fairly different things. Creating a custom tab involves adding the Teams JavaScript SDK to the hosted content page and using that SDK to communicate with Teams.

 

Adding a website tab on the other hand just embeds the URL you provide in a web view. it cannot communicate with Teams, and there are no expectations on behavior.

Essentially you can not just add any URL to a custom tab in app. You have to customize that page to work as part of  an app. Please take a look  at the Add Tabs to Microsoft Teams.

 

We support Ukraine and condemn war. Push Russian government to act against war. Be brave, vocal and show your support to Ukraine. Follow the latest news HERE