Dart - how _InternalLinkedHashMap<String, dynamic> convert to Map<String, dynamic>?

Try this:

Map<String, dynamic>.from(yourData)

You don't need to do any conversion. _InternalLinkedHashMap<K, V> is already a type of Map<K, V>.

void main() async {
  final map = <String, int>{};
  print(map.runtimeType);
  print('${map is Map<String, int>}');
}

prints:

_InternalLinkedHashMap<String, int>
true

(Map's default constructor is a factory constructor that constructs a LinkedHashMap. LinkedHashMap's default constructor is also a factory constructor, and the implementation for the Dart VM constructs and returns an internal _InternalLinkedHashMap object.)