I also face this issue, and many others are experiencing it as well.

Here is the correct link (which is not showing in the App Store when we log in and try to find in-app purchases). However, if you use this link, it will redirect you to the App Store in-app purchase API page.

Please make sure to log in as the owner, not as a developer or admin:

https://appstoreconnect.apple.com/access/integrations/api/subs