What's wrong with tabbar color effect on iOS 26?

In my project, the window.rootViewController is a UITabBarController containing four UIViewControllers. The first, third, and fourth VCs are empty, while the second VC's view hierarchy is structured as follows:

UIViewController.view
├── UIScrollView (contentSize: self.view.width * 2, 0; backgroundColor: .red)
    ├── UIScrollView (contentSize: 0, self.view.height * 2; backgroundColor: .black)
     └── UIScrollView (contentSize: 0, self.view.height * 2; backgroundColor: .white)

When I switch to the second tab and horizontally scroll the scrollView, the tabBar color doesn't adapt to the current view's dominant color. However, if I launch the app and sequentially tap every tab before switching to the second tab, the tabBar color then changes dynamically during horizontal scrolling. But if I background the app and return, the tabBar reverts to black.

Why does this happen? How can I either: Manually control the tabBar color, or Make it automatically match the page's dominant color?

This issue occurs when the "Reduce Transparency" accessibility setting is enabled.

What's wrong with tabbar color effect on iOS 26?
 
 
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