I think this is just very inconsistent behaviour for Simulator. Since iOS 14, we can test on the Simulator, and I used App Store subscriptions using the Simulator just a few weeks ago. Even in the issue you linked, someone is saying how it was working until a few days before their post. However, the Simulator is even refusing to allow me to log in to the Sandbox account. RevenueCat has docs on how to use Subscriptions and IAPs in Simulator, so it definitely seems like an issue with Simulator itself. I would link to RevenueCat but, apparently, the RevenueCat docs "is not a permitted domain on this forums".