How to convert String into List of dynamic in flutter - flutter

Question

I am working on a flutter project with firebase.
When I tried to fetch data ({id: 2021-10-13 04:48:15.582, title: Red Shirt, quantity: 1, price: 29.99}, {id: 2021-10-13 04:48:19.438, title: Mobile Phone, quantity: 1, price: 215})
So, I want to convert each map to a list of dynamic because I got this error
Error: Expected a value of type 'List< dynamic>', but got one of type 'String'
here is my code to fetch data
Future<void> fetchandSetOrders() async {
const url = "https://test-app.firebaseio.com/orders.json";
final response = await http.get(Uri.parse(url));
final List<OrderItem> loadedOrders = [];
final extractedData = json.decode(response.body) as Map<String, dynamic>;
if (extractedData == null) {
return;
}
extractedData.forEach((orderId, orderData) {
print(orderData['products']);
print(orderData['products'].runtimeType);
loadedOrders.add(
OrderItem(
id: orderId,
amount: orderData['amount'],
dateTime: DateTime.parse(orderData['dateTime']),
products: (orderData['products'] as List<dynamic>)
.map(
(item) => CartItem(
id: item['id'],
price: item['price'],
quantity: item['quantity'],
title: item['title'],
),
)
.toList(),
),
);
});
_orders = loadedOrders.reversed.toList();
notifyListeners();}