With iOS 15, Apple adds the scrollEdgeAppearance
property for configuring the appearance of the tab bar while edge scrolling.
To fix the transparent tab bar, you should create a custom scroll edge appearance and set it to the tab bar.
if #available(iOS 15.0, *) {
let appearance = UITabBarAppearance()
appearance.backgroundEffect = UIBlurEffect(style: .light)
tabBar.scrollEdgeAppearance = appearance
}