Menu bar sometimes shows solid black or random background instead of staying transparent

After updating to macOS Tahoe 26.0 the menu bar does not remain fully transparent when “Automatically hide and show the menu bar” is enabled and “Transparent” style is selected.

When an application window is underneath the menu bar and I move the pointer to reveal it, the bar sometimes:

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• appears as a completely black strip,
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• briefly shows parts of the desktop wallpaper, or
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• 
  
• displays only a thin underline instead of a smooth blur/transparent look.
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The issue happens randomly and disappears if no window is beneath the menu bar.

Steps to Reproduce

1. 
   
2. In System Settings ▸ Desktop & Dock, set Menu Bar Style to Transparent.
3. 
   
4. 
   
5. Enable Automatically hide and show the menu bar.
6. 
   
7. 
   
8. Open any full-screen or maximized window (Safari, Finder, etc.) that sits behind the menu bar area.
9. 
   
10. 
    
11. Move the cursor to the top edge to reveal the menu bar.
12. 
    

Expected Result

Menu bar should reveal with consistent transparency/blur and no solid color or wallpaper artifact.

Actual Result

Menu bar sometimes shows a solid black background, a highlighted underline, or flashes of the desktop wallpaper.

Configuration

– macOS Tahoe 26.0 (final release)

– Mac mini [m4]

– Occurs in both Light and Dark appearance modes.

Additional Notes

Restarting Dock or toggling menu-bar settings temporarily fixes it, but the problem returns. Appears to be a rendering bug in 26.0.