Same here. We have never had this issue before. Everything was working fine until yesterday(Europe Time zone).

It’s working. Apps from TestFlight can be installed again. We didn't make any changes. Thanks Apple🍎

Try use appAccountToken() you can set appAcountToken with your custom token (with user data) then app store server will send your token in the payload in transaction body. Read this https://developer.apple.com/documentation/storekit/product/purchaseoption/3749440-appaccounttoken

What about appAccountToken()? You can set token app account token in a app with your token containg user data. Then App Store Server will send you this token in transaction payload from notification. https://developer.apple.com/documentation/storekit/product/purchaseoption/3749440-appaccounttoken