Flutter textFiled input is always save the change in AlertDialog widget

I have problem that create cancel button in textField.

But it’s always save changing cancel button and submit button both

If I delete the cancel button code, it’s also save the change of textField when pop alertdialog by clicking background

I find some video and document but there is not different in code

https://www.youtube.com/watch?v=TpW7nLL57uQ

Below: My AlertDialog code

Future<void> editField(String field) async {
    String newValue = '';
    await showDialog(
      context: context,
      builder: (context) => AlertDialog(
        backgroundColor: Colors.grey[100],
        title: Text(
          "Edit $field",
          style: const TextStyle(color: Colors.black),
        ),
        content: TextField(
          autofocus: true,
          style: const TextStyle(color: Colors.black),
          decoration: InputDecoration(
            hintText: "Enter new $field",
            hintStyle: const TextStyle(color: Colors.grey),
          ),
          onChanged: (value) {
            newValue = value;
          },
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context),
            child: const Text('Cancel'),
          ),
          TextButton(
            onPressed: () => Navigator.of(context).pop(newValue),
            child: const Text('Submit'),
          ),
        ],
      ),
    );
    if (newValue.trim().isNotEmpty) {
      await userCollection.doc(currentUser.email).update({field: newValue});
    }
  }