Why the screen becomes dark when an alert was displaying with flutter?

I don't know why the screen becomes dark when I try to use the alert on initState() in my flutter application. This is the code :

  if (element.isCharacteristic42) {
             
         
              Scaffold:
              (showDialog(
                  context: context,
                  builder: (context) {
                    return AlertDialog(
                      title: Text('Be Careful an obstacle was detected'),
                      backgroundColor: Color.fromARGB(45, 231, 148, 54),
                      alignment: Alignment.topCenter,
                    );
                  }));
            }

Thanks in advance for your help

The outer shadow is provided by barrierColor of showDialog. You can make it transparent.

And to show dialog inside initState, use addPostFrameCallback to complete the first frame

  @override
  void initState() {
    super.initState();

    WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
      showDialog(
        context: context,
        barrierColor: Colors.transparent,