The post TN3138: Handling App Store receipt signing certificate changes mentioned that receipt hashing algorithm in Sandbox and TestFlight will both change to SHA256 after 2023/8/16. However this never happened. Our apps were still getting SHA1 receipt in dev environment. Only after we had published our app, the "real store" started to send us SHA256 encrypted receipts. This is so confusing.
(We're using iOS 16.6+ device for testing)