Instagram business OAuth login intermittently shows incorrectly redirecting to FB login

Our IG Business OAuth URL is:
https://www.instagram.com/oauth/authorize?enable_fb_login=0&force_authentication=1&client_id=1308449337003790&redirect_uri=https://tunnel.virrally.com/api/instagram/callback&response_type=code&scope=instagram_business_basic%2Cinstagram_business_manage_messages%2Cinstagram_business_manage_comments
It is clear from the url that FB login is disabled and forced auth is enabled.
Now if you try to hit that URL, it will intermittently redirect to a login page where we see FB login option. From this window, logging in with instagram also fails with an error:
Invalid request: Request parameters are invalid: Invalid scope: instagram_business_basic
It redirects to the correct page intermittently and login is successful from that page.
To reproduce, you can try hitting that URL repeatedly and you will see 2 different login windows intermittently. Attaching both screenshots too.
Any idea how to stop FB window from showing up? Seems like that is not meant for business login and it still comes up because of some flawed redirection logic at Instagram end.