### Preflight Checklist

- [X] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
- [X] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
- [X] I have searched the [issue tracker](https://www.github.com/electron/electron/issues) for a feature request that matches the one I want to file, without success.

### Electron Version

13.0.0-beta.16

### What operating system are you using?

macOS

### Operating System Version

macOS Big Sur 11.2.1

### What arch are you using?

x64

### Last Known Working Electron version

12.0.5

### Expected Behavior

When viewing a window in mission control the shadow shouldn't change.

### Actual Behavior

When viewing a window with vibrancy set to 'under-window' and titleBarStyle set to 'hidden' or 'hiddenInset' in mission control the shadow of the window is too small. 

It only seems to happen when the window is in focus and when there are multiple windows on the screen. The behaviour can sometimes persist when going from mission control to normal view. 

See the window at the bottom left in the screenshot.

<img width="1195" alt="Screenshot" src="https://user-images.githubusercontent.com/54709288/115758066-a397f980-a396-11eb-9ecc-c97e670b3b82.png">



### Testcase Gist URL

_No response_
shell/browser/native_window_mac.h
void SetEscapeTouchBarItem(gin_helper::PersistentDictionary item) override;
  void SelectPreviousTab() override;
  void SelectNextTab() override;
  void MergeAllWindows() override;
  void MoveTabToNewWindow() override;
  void ToggleTabBar() override;
  bool AddTabbedWindow(NativeWindow* window) override;
  void SetAspectRatio(double aspect_ratio,
                      const gfx::Size& extra_size) override;
  void PreviewFile(const std::string& path,
                   const std::string& display_name) override;
  void CloseFilePreview() override;
  gfx::Rect ContentBoundsToWindowBounds(const gfx::Rect& bounds) const override;
  gfx::Rect WindowBoundsToContentBounds(const gfx::Rect& bounds) const override;
  void NotifyWindowEnterFullScreen() override;
  void NotifyWindowLeaveFullScreen() override;
  void NotifyWindowWillEnterFullScreen();
  void NotifyWindowWillLeaveFullScreen();
  
  
  
  void Cleanup();
  
  void OverrideNSWindowContentView();
  void UpdateVibrancyRadii(bool fullscreen);
  
  void SetStyleMask(bool on, NSUInteger flag);
  void SetCollectionBehavior(bool on, NSUInteger flag);
  void SetWindowLevel(int level);
  enum class FullScreenTransitionState { ENTERING, EXITING, NONE };