How to change a TabBar location in iOS 14

In my app I want to be able to place a UIView under my TabBar (to use ad banner). I successfully implemented the UIView, but I can't change the TabBar location (the TabBar to be above the UIView). I try solutions for iOS 13 and early but they don't work on iOS 14. My UIView still is in the foreground over the TabBar.

An example of how I want it to be:

My code now:

class MainTabBarController: UITabBarController {
...
lazy var bannerAd: UIView = {
   let view = UIView()
   view.translatesAutoresizingMaskIntoConstraints = false
   view.backgroundColor = .green
   return view
}()
...
override func viewDidLoad() {
   super.viewDidLoad()
   view.addSubview(bannerAd)
   bannerAd.heightAnchor.constraint(equalToConstant: 44).isActive = true
   bannerAd.bottomAnchor.constraint(equalTo: self.view.bottomAnchor).isActive = true
   bannerAd.widthAnchor.constraint(equalTo: self.view.widthAnchor).isActive = true
}
...
override func viewWillLayoutSubviews() {
   super.viewWillLayoutSubviews()
   self.tabBar.invalidateIntrinsicContentSize()
   var tabFrame = self.tabBar.frame
   tabFrame.size.height = tabBarHeight
   tabFrame.origin.y = tabFrame.origin.y - 44
   self.tabBar.frame = tabFrame
   }
}