getx `Get.previous` returns wrong route?

I need to track every routing between pages with its previous page. I created my own observer class and passed it on routingCallback in GetMaterialApp. But i found that Get.previous returns wrong value. When i tried to dig through the Routing class, i found that the value.previous is assigned with wrong value.

@override
  void didPop(Route route, Route? previousRoute) {
    super.didPop(route, previousRoute);
    final currentRoute = _RouteData.ofRoute(route);
    final newRoute = _RouteData.ofRoute(previousRoute);

    if (currentRoute.isSnackbar) {
      // Get.log("CLOSE SNACKBAR ${currentRoute.name}");
      Get.log("CLOSE SNACKBAR");
    } else if (currentRoute.isBottomSheet || currentRoute.isDialog) {
      Get.log("CLOSE ${currentRoute.name}");
    } else if (currentRoute.isGetPageRoute) {
      Get.log("CLOSE TO ROUTE ${currentRoute.name}");
    }
    if (previousRoute != null) {
      RouterReportManager.reportCurrentRoute(previousRoute);
    }

    // Here we use a 'inverse didPush set', meaning that we use
    // previous route instead of 'route' because this is
    // a 'inverse push'
    _routeSend?.update((value) {
      // Only PageRoute is allowed to change current value
      if (previousRoute is PageRoute) {
        value.current = _extractRouteName(previousRoute) ?? '';
        value.previous = newRoute.name ?? ''; <-- isn't this supposed to be currentRoute.name?
      } else if (value.previous.isNotEmpty) {
        value.current = value.previous;
      }

      value.args = previousRoute?.settings.arguments;
      value.route = previousRoute;
      value.isBack = true;
      value.removed = '';
      value.isSnackbar = newRoute.isSnackbar;
      value.isBottomSheet = newRoute.isBottomSheet;
      value.isDialog = newRoute.isDialog;
    });

    // print('currentRoute.isDialog ${currentRoute.isDialog}');

    routing?.call(_routeSend);
  }

Let's say the app navigates from A to B, then go back to A. In this case, the previous page should be the B instead of A. Is the Get.previous supposed to return that value? or it is just me who misunderstand about using routingCallback?

Here's the observer class i made :

class Middleware {
  static observer(Routing routing) {
    switch (routing.current) {
      case FirstPage.routeName:
        debugPrint('first page tracker from ${routing.previous}');
        break;
      case SecondPage.routeName:
        debugPrint('second page tracker from ${routing.previous}');
        break;
    }
  }
}

Thanks!

To Reproduce Steps to reproduce the behavior: