Certain apps do not comply with App Policies
My organisation is a government agency where we hold security and governance very tight. Recently we noticed on Teams desktop/web client the Stream and Wiki apps do not comply with the org-wide app policy or the app policy assigned to users.
In our organisation we disabled all Microsoft and 3rd party apps from Teams client, and it worked until a couple of months ago with Teams client updates the Stream and Wiki apps started showing up. They seem to ignore the app policies. And there is no way to hide them.