Repository: flutter
Issue: Blur filter issue on iOS when animating a blurred widget
Labels: platform-ios,engine,a: animation,a: platform-views,has reproducible steps,P2,found in release: 3.3,found in release: 3.6,team-ios,triaged-ios

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## Steps to Reproduce

<!-- Please include full steps to reproduce so that we can reproduce the problem. -->

1. [GitHub repo](https://github.com/mario-jerkovic/flutter_platform_blur_issue/tree/bug_animation) with reproducible example
2. Checkout on branch "bug_animation"
3. Run the app on iOS device, preferably iOS simulator

**Expected results:** <!-- what did you want to see? -->

Animated blurred widget should animate without creating any blur effect on other widgets

**Actual results:** <!-- what did you see? -->

When the blurred widget animates in (from left to right edge of the screen), there is a visible blur entering from the right edge of the screen following the animation of the widget, so instead of the blur only happening on the left side, it also happens on the right side. When the widget is animating out (from right to left edge of the screen), the blur effect is also animating out. Seems like the blur effect is mirrored compared to the behaviour of the widget. On the screenshots, the green border show the widget that is animating in, and the red border the unwanted blur effect.

<details>
<summary>Code</summary>

```dart
// Moveable.dart
// Moveable widget wraps any child widget passed with Positioned and Gesture detector
// and updates the Positioned top and left properties with current x and y position
// of the pointing device (touch or mouse)

 Positioned(
        top: _y,
        left: _x,
        child: GestureDetector(
          onPanUpdate: (details) {
            setState(() {
              _y += details.delta.dy;
              _x += details.delta.dx;
            });
          },
          child: widget.child,
        ),
      ),
```

```dart
// Translatable.dart
// Translatable widget wraps foreground and background widgets passed and translates between them
// using SlideTransition and FadeTransition

AnimatedBuilder(
      animation: _animationController.view,
      builder: ((context, child) {
        return Stack(
          children: [
            if (_backgroundSheet != null)
              SlideTransition(
                position: _backgroundSlideAnimation,
                child: FadeTransition(
                  opacity: _backgroundFadeAnimation,
                  child: Transform.scale(
                    scale: _backgroundScaleAnimation.value,
                    child: _backgroundSheet,
                  ),
                ),
              ),
            if (_foregroundSheet != null)
              SlideTransition(
                position: _foregroundSlideAnimation,
                child: FadeTransition(
                  opacity: _foregroundFadeAnimation,
                  child: Transform.scale(
                    scale: 1,
                    child: _foregroundSheet,
                  ),
                ),
              ),
          ],
        );
      }),
    );
```

```dart
// main.dart
// Renders Stack with Google Maps widget and Translatable widget which translates a widget onto the map
Translatable(
    foreground: BlurredBlock0(),
    background: BlurredBlock1(),
),
```
</details>

<details>
  <summary>Logs</summary>

```

[✓] Flutter (Channel master, 3.5.0-12.0.pre.175, on macOS 13.0 22A380 darwin-x64, locale en-HR)
    • Flutter version 3.5.0-12.0.pre.175 on channel master at /Users/erikkiralj/flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 92f10ed712 (2 weeks ago), 2022-11-08 17:57:52 -0800
    • Engine revision e7d7edab98
    • Dart version 2.19.0 (build 2.19.0-374.0.dev)
    • DevTools version 2.19.0

[✓] Android toolchain - develop for Android devices (Android SDK version 32.0.0)
    • Android SDK at /Users/erikkiralj/Library/Android/sdk
    • Platform android-33, build-tools 32.0.0
    • Java binary at: /Users/erikkiralj/Library/Application Support/JetBrains/Toolbox/apps/AndroidStudio/ch-0/213.7172.25.2113.9123335/Android Studio.app/Contents/jre/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 11.0.13+0-b1751.21-8125866)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 14.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 14B47b
    • CocoaPods version 1.11.3

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 2021.3)
    • Android Studio at /Users/erikkiralj/Library/Application Support/JetBrains/Toolbox/apps/AndroidStudio/ch-0/213.7172.25.2113.9123335/Android Studio.app/Contents
    • 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 11.0.13+0-b1751.21-8125866)

[✓] Android Studio (version 2021.2)
    • Android Studio at /Users/erikkiralj/Library/Application Support/JetBrains/Toolbox/apps/AndroidStudio/ch-0/212.5712.43.2112.8815526/Android Studio.app/Contents
    • 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 11.0.12+0-b1504.28-7817840)

[✓] VS Code (version 1.73.1)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.52.0

[✓] Connected device (3 available)
    • iPad Pro (12.9-inch) (6th generation) (mobile) • ACDD46C2-E0C9-4F97-8E7C-DF60FC3EDF80 • ios            • com.apple.CoreSimulator.SimRuntime.iOS-16-1 (simulator)
    • macOS (desktop)                                • macos                                • darwin-x64     • macOS 13.0 22A380 darwin-x64
    • Chrome (web)                                   • chrome                               • web-javascript • Google Chrome 107.0.5304.110

[✓] HTTP Host Availability
    • All required HTTP hosts are available

• No issues found!

```

</details>

**Video example** 

https://user-images.githubusercontent.com/94460559/203551914-b578ef7d-4f02-4bf2-b590-b0bd1b5b4570.mp4

<img width="648" alt="Screenshot 2022-11-23 at 15 38 53" src="https://user-images.githubusercontent.com/94460559/203575123-6488f808-bae6-49a8-b773-b5c4134f7717.png">
<img width="648" alt="Screenshot 2022-11-23 at 15 39 08" src="https://user-images.githubusercontent.com/94460559/203575144-eff90631-b1fc-459e-98ad-cfa67ac4e9a5.png">