Flutter bottom sheet height changed while keyboard is shown

i am developing a bottom sheet which contains a TextField, i noticed that every time the keyboard is shown, the bottom sheet’s height reduced, then recovered when keyboard is hidden, this is my demo code

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      resizeToAvoidBottomInset: false,
      body: Center(
        child: ElevatedButton(
          onPressed: () {
            showModalBottomSheet(
              context: context,
              builder: (_) {
                return const SafeArea(
                  child: SizedBox(
                    height: 500,
                    child: TextField(),
                  ),
                );
              }
            );
          },
          child: const Text("show bottom sheet"),
        ),
      )
    );
  }
}

perhaps is the SafeArea became hidden when keyboard is shown? how can i keep the bottom sheet’s hight the same while keyboard is shown