Unsafe cryptographic encryption patterns" - How I can fixed this error?

Question

Few days ago, In "Pre-launch report for APK" in Google Play Console, it start to flag me This example my code i need to solution fixed

Future<LoginResponse> login(
  {required String nationalId, required String pin}) async {
try {
  print(pin);
  final response = await _client.post('/login',
      data: {
        'id': nationalId.replaceAll('-', ''),
        'pin': pin,
      },
      options: Options(headers: {"requiresToken": false}));

  final Map<String, dynamic> data = response.data;
  final String token = data['data']['token'];
  await sharedPref.setString("BearerToken", token);
  final profileData = await me();
  return profileData;
} catch (e) {
  throw onDioError(e);
}}

and this my results from pre launch