Hi, am facing the same issue in iOS 15 RC, Xcode 13 RC in all of my apps, in iOS 14 it works fine. The SKProductRequest, no methods get called, neither fail nor success. Also, we observed that it start happening when the app status in Testflight changes to RENEW.
Once it happen in sandbox then it also start happening in our/third party live apps, i.e one that are downloaded from Appstore.
What we checked
All Agreement Accepted.
Banking details proper
Certificate and profiles proper
In-app and bundle id proper
Checked with multiple sandbox and live accounts.
Strange thing is it works until the testflight app status changes to "RENEW".