We are experiencing the same problem. It looks like there are something wrong in their side. Their status show all services working fine, but after trying several times we couldn't get a successful response. https://developer.apple.com/system-status/

Hi, is the offerType 1 unset when the user starts paying? I need to identify whether a transaction is converted from the trial period and starts paying. So my idea is to get the transaction history and check if offerType from the current transaction is unset and offerType from the previous transaction is 1. Is this approach correct? Is there any other way to achieve this without getting the transaction history? Thanks in advance.

Same problem here. We are responding with a 200 status code but we starting to receive so many duplicated notifications. The unified_receipt.latest_receipt containing the receipt token is the only field that changes. In our case, the token is a valid Base64 and we can get the receipt with it. And comparing both receipts the only difference between them is the receipt_creation_x, request_date_x and original_puchase_date_x timestamps. For this reason, our ratio of received notifications suddenly increased from ~50/h to ~200/h and it remains stable in that range causing several issues related to our revenue metrics.