when am using

CodePudding user response：

I think you need are not using latLng2

dependencies:
  latlong2: ^0.8.0

import 'package:latlong2/latlong.dart' as latLng;

FlutterMap(
      options: MapOptions(
       center: latLng.LatLng(51.509364, -0.128928),
        zoom: 9.2,
      ),