You probably shouldn't use your login page as Start URL

The Start URL is the page that opens when a user taps your app icon on their home screen.

Choose a URL that takes logged-in users straight into the main experience of your app—such as a dashboard or primary feature. Logged-out users should be redirected to your login page.

Avoid setting your login page as the Start URL. In most cases, this will cause users to be prompted to log in again every time they open your app.

Exception: If your login page can automatically detect authenticated users and immediately redirect them to the dashboard, using it as the Start URL may be acceptable.