Repository: flutter
Issue: Android TalkBack Item label warning for the whole screen when using a11y scanner
Labels: platform-android,engine,a: accessibility,has reproducible steps,P2,found in release: 3.0,found in release: 3.1,customer: castaway,team-android,triaged-android

When I'm testing the simplest Hello World application by TalkBack I receive a warning 
"This item may not have a label readable by screen readers" for the whole screen. Btw the Google Console internal testing shows the same issue.

![photo_2022-05-29_06-50-39](https://user-images.githubusercontent.com/8906519/170849872-d8308fd6-13c2-4f40-bd6f-909e2387754d.jpg)

I've already tried to wrap the Scaffold, and the MaterialApp in Semantics widget. It doesn't help.

<details>
<summary>Code</summary>

```
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: 'Hello',
      debugShowCheckedModeBanner: false,
      home: MainScreen(),
    );
  }
}


class MainScreen extends StatelessWidget {
  const MainScreen({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Hello world'),
      ),
      body: const Center(
        child: Text('Hello world!'),
      ),
    );
  }
}

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  if(RendererBinding.instance != null){
    RendererBinding.instance!.setSemanticsEnabled(true);
  }
  runApp(const MyApp());
}
```
</details>
<details>
  <summary>Logs</summary>

```
[√] Flutter (Channel stable, 2.10.5, on Microsoft Windows [Version 10.0.19044.1706], locale ru-RU)
    • Flutter version 2.10.5 at C:\flutter\flutter_windows_2.8.0-stable\flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 5464c5bac7 (6 weeks ago), 2022-04-18 09:55:37 -0700
    • Engine revision 57d3bac3dd
    • Dart version 2.16.2
    • DevTools version 2.9.2

[√] Android toolchain - develop for Android devices (Android SDK version 32.0.0)
    • Android SDK at C:\Users\Futuro\AppData\Local\Android\sdk
    • Platform android-32, build-tools 32.0.0
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 11.0.11+9-b60-7590822)
    • All Android licenses accepted.

[√] Chrome - develop for the web
    • Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe

[X] Visual Studio - develop for Windows
    X Visual Studio not installed; this is necessary for Windows development.
      Download at https://visualstudio.microsoft.com/downloads/.
      Please install the "Desktop development with C++" workload, including all of its default components

[√] Android Studio (version 2021.1)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 11.0.11+9-b60-7590822)

[√] Connected device (4 available)
    • SM G935F (mobile) • ad06170246004eb408 • android-arm64  • Android 8.0.0 (API 26)
    • Windows (desktop) • windows            • windows-x64    • Microsoft Windows [Version 10.0.19044.1706]
    • Chrome (web)      • chrome             • web-javascript • Google Chrome 102.0.5005.62
    • Edge (web)        • edge               • web-javascript • Microsoft Edge 101.0.1210.47

[√] HTTP Host Availability
    • All required HTTP hosts are available

```

</details>

How can I get rid of that warning? Please, help me solve this problem.