GetxController value change listen is called without widget init

[magic3584]

Describe the bug
I have a manager which extends the GetxController. The manager has a timer and start counting down when push to a new page.
I have 3 pages that are A->B->C, the manager restart timer when push to B and C, and C.page looks like

@override
  void initState() {
    // TODO: implement initState
    super.initState();
    WidgetsBinding.instance.addPostFrameCallback((_) {
      countManager.startCountDown(10);
      countManager.count.listen((value) {
        if (countManager.isCounting &&
            value == 0 &&
            Get.currentRoute == '/CourierQrcodePage') {
          debugPrint("value---------:$value");
          debugPrint('_pushToHomePage');
          countManager.stopCountDown();
          Get.until((route) => route.isFirst);
        }
      }); 
    });
  }

It works fine the first time and C has been disposed. But when I push like A->B, the debugPrint has show without C init. Why? And another question is that when I push to C, it back to A immediately.
Flutter Version:
3.13.9

Getx Version:
4.6.6