I can confirm that the issue still exists. Just released a new app that uses SubscriptionStoreView(groupID: "someGroupId"). I tested on Simulator and Test Flight, there were no issues at all. After the app is approved and released, I got a message from a user who was complaining about the "Subscription unavailable" screen on my app. I didn't test my app after the release because I thought if everything works on Test Flight, there shouldn't be any issues on the App Store.
After the message, I installed the app and got the same error. Then, I implemented the change, SubscriptionStoreView(productIDs: ["someProductId1", "someProductId2"]) and submitted a fix this morning. The app is just approved, I installed the new version and the store page works now.
It is really sad that Apple is not acknowledging this issue and trying to fix it. I shared my app yesterday on LinkedIn and my landing page got hundreds of visitors. Probably I missed a lot of sales because of the bug in the StoreKit API. I guess from now on, I will need to test my app not only on Test Flight but also on the App Store.
@SPEEDCUP thank you for sharing the workaround!