Repository: flutter
Issue: Surrounding color leaks into widgets when BackdropFilter with ImageFilter.blur is applied
Labels: framework,engine,f: material design,has reproducible steps,P2,found in release: 2.10,found in release: 2.11,team-design,triaged-design

I'm having an issue with a GridView of blurred tiles using `BackdropFilter with ImageFilter.blur` where any surrounding color leaks into them:

![imagefilter_blur_issue](https://user-images.githubusercontent.com/1992115/156901663-c02e981c-29fc-4b41-bc27-91ac3853f3f1.png)

![ImageFilter_blur_issue_white_color](https://user-images.githubusercontent.com/1992115/156901757-1f0f29d9-13d5-4dc8-8aa3-ffcd0847d861.png)

Here is a Dartpad example: https://dartpad.dev/?id=1196002918293fdd251557b037d2d786

<details>
<summary>Here is the code sample:</summary>

```dart
import 'dart:ui';
import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'ImageFilter Color Leak Issue',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        backgroundColor: Colors.white,
        appBar: AppBar(
          title: const Text('ImageFilter.blur Color Leak Issue'),
        ),
        body: Column(
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          children: [
            Expanded(
              child: Container(
                color: Colors.white,
                width: double.infinity,
                child: FittedBox(
                  fit: BoxFit.contain,
                  child: Padding(
                    padding: const EdgeInsets.all(40),
                    child: Container(
                      width: 400,
                      height: 400,
                      color: const Color(0xFF0000FF),
                      child: GridView.count(
                        padding: EdgeInsets.zero,
                        shrinkWrap: true,
                        physics: const NeverScrollableScrollPhysics(),
                        crossAxisCount: 3,
                        children: tiles(),
                      ),
                    ),
                  ),
                ),
              ),
            ),
            Expanded(
              child: Container(
                color: Colors.black,
                width: double.infinity,
                child: FittedBox(
                  fit: BoxFit.contain,
                  child: Padding(
                    padding: const EdgeInsets.all(40),
                    child: Container(
                      width: 400,
                      height: 400,
                      color: const Color(0xFF0000FF),
                      child: GridView.count(
                        padding: EdgeInsets.zero,
                        shrinkWrap: true,
                        physics: const NeverScrollableScrollPhysics(),
                        crossAxisCount: 3,
                        children: tiles(),
                      ),
                    ),
                  ),
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  List<Widget> tiles() => List<Widget>.generate(
        9,
        (_) => ClipRRect(
          child: BackdropFilter(
            filter: ImageFilter.blur(
              sigmaX: 20,
              sigmaY: 20,
            ),
            child: Container(
              decoration: BoxDecoration(
                color: Colors.white.withOpacity(0.2),
                borderRadius: BorderRadius.circular(12),
              ),
            ),
          ),
        ),
      );
    }
```
</details>

<details>
<summary>flutter doctor:</summary>

```
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 2.10.3, on macOS 11.5.1 20G80 darwin-x64, locale en-US)
[✓] Android toolchain - develop for Android devices (Android SDK version 31.0.0)
[✓] Xcode - develop for iOS and macOS (Xcode 13.2.1)
[✓] Chrome - develop for the web
[✓] Android Studio (version 2020.3)
[✓] VS Code (version 1.66.0-insider)
[✓] Connected device (1 available)
    ! Device emulator-5562 is offline.
[✓] HTTP Host Availability

• No issues found!
```
</details>