Or I could only receive notification in production environment and Sandbox environment?

I find Apple will try billing user up to 60 days, if user doesn't cancel his subscription. But we consider the user terminated this subscription when the grace period runs out. So if the user resubscribe the streamer in other platform(Android or Web), and then Apple successfully billing the user. It will cause the user being billed twice!! So I wonder whether developer could cancel user's subscription, or is there any good practice for this situation? https://developer.apple.com/documentation/storekit/in-app_purchase/subscriptions_and_offers/handling_subscriptions_billing Billing-related issues trigger the subscription to enter a billing retry state where the App Store attempts to renew the subscription for up to 60 days.

I find in document https://help.apple.com/app-store-connect/#/devb57be10e7 Last sentence in tip2's paragraph 2. "See Add an in-app purchase to use App Store Connect to add your in-app purchase, or App Metadata Specifications to use XML." So, Apple only supports creating product by XML or Manually(App Store Connect) ? Is there any good practice for Live stream subscriptions?(Every streamer could be subscibed, and every one could be a steamer, that means the auto-renew subscripion products could be many and dynamically)?

ok for me. Indexing doesn't show in the processing bar, and delay after building, that makes I can't find any "callers" for any methods and properties at that moment