Custom authentication in preview environments does not work

**Describe the bug**
We are trying to use named preview environments with an static web app that uses custom entra id autentication. The preview environment doesnot work with authentication.

**To Reproduce**
1. Configure custom entra id authentictaion on the production environment and verify that it work.
2. Deploy a named preview environment, and the authentication does not work.

**Expected behavior**
Im expection authentication to work on preview enviroments, with out authentication i cant access the preview environment as we have disabled annonymous access.