flutter: Can't detect subscription renewal (in_app_purchase)

I'm using a tool called in_app_purchase (version: ^3.1.4 ) to manage subscriptions in my app. It's working well, and I'm able to give users access to the product they're subscribing to.

Right now, my app is in test mode. I get emails from Google to let me know if a subscription has been canceled, renewed, or if it's new.

When a subscription is renewed, I want to know about it so I can update the user's account. To do that, I use a method called restorePurchases() to check past purchases. I then compare the date of the latest purchase with the one I have stored in my FireStore database. If the new purchase is more recent than the last one, I update the user's account and give them access to the product they're subscribed to.

Bellow is how I implemented that logic:

• initState method:

  @override
     void initState() {
       super.initState();
  
       final Stream purchaseUpdated = _inAppPurchase.purchaseStream;
       _subscription = purchaseUpdated.listen(
         (purchaseDetailsList) {
           loggy.info("I AM LISTENING....");
           _listenToPurchaseUpdated(purchaseDetailsList);
         },
         onDone: () {
           _subscription.cancel();
         },
         onError: (error) {
           // handle error here.
         },
       );
       _inAppPurchase.restorePurchases();//here I trigger the purchaseStream each time initState is called
     }
  

_listenToPurchaseUpdated method:

Future<void> _listenToPurchaseUpdated(purchaseDetailsList) async {
    for (final PurchaseDetails purchaseDetails in purchaseDetailsList) {
      if (purchaseDetails.status == PurchaseStatus.pending) {
        showPendingUI();
      } else {
        if (purchaseDetails.status == PurchaseStatus.error) {
          hendleError(purchaseDetails);
        } else if (purchaseDetails.status == PurchaseStatus.purchased ||
            purchaseDetails.status == PurchaseStatus.restored) {
          if (!mounted) return;

          final lastTransactionDate =
              await SubscriptionService().getLastTransactionDate();
          if (lastTransactionDate.isNotEmpty) {
            loggy.info(
              "last transaction date: $lastTransactionDate",
            );
          }
          loggy.info(
            "current transaction date: ${purchaseDetails.transactionDate}",
          );

          if (lastTransactionDate.isEmpty ||
              lastTransactionDate != purchaseDetails.transactionDate) {
            final bool isRecentRenewal = DateTime.fromMillisecondsSinceEpoch(
              int.parse(purchaseDetails.transactionDate!),
            ).isAfter(
              DateTime.fromMillisecondsSinceEpoch(
                int.parse(lastTransactionDate),
              ),
            );

            if (isRecentRenewal) {
              loggy.info("delivering product in progress....");
              await deliverProduct(purchaseDetails);
            }
          }
        }

        if (purchaseDetails.pendingCompletePurchase) {
          await _inAppPurchase.completePurchase(purchaseDetails);
        }
      }
    }
}

In the above method, I'm just getting the last transactionDate that was stored in FireStore and comparing it with the current transactionDate, this field can be found on:

purchaseDetails.transactionDate

Unfortunately, when the subscription is renewed, I can't detect it in the app, and the transactionDate remains the same:

from flutter: Can't detect subscription renewal (in_app_purchase)