GetX/Material issue with locales

main.dart

import 'package:flutter/material.dart';
import 'package:get/get.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return GetMaterialApp(
      supportedLocales: [Locale('es'), Locale('en')],
      locale: Locale('es'), /// "es" locale not found in Material and fallback doesnt work.
      /// fix:
      /// localeResolutionCallback: (_, __) => Locale('en'),
      fallbackLocale: Locale('en'),
      translationsKeys: {'en': {}, 'es': {}}, /// irrelevant for Material
      home: HomePage(),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('locales bug')),
    );
  }
}

pubspec.yaml

name: getx_test
description: test for intl8 issue
publish_to: 'none'
version: 1.0.0+1
environment:
  sdk: ">=2.13.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  get: ^4.1.4

dev_dependencies:
  flutter_test:
    sdk: flutter
flutter:
  uses-material-design: true