UISearchController SearchBar height changes unexpectedly when text field selected

General remarks:

• iOS 13.5
• The desired behavior is for the bar to (1) remain visible, (2) it's original position, (3) even when selected and the keyboard appears.
• The problem only occurs when the UISearchBar obtained using a UISearchController. The problem does not appear when a UISearchBar is instantiated directly.
• The parent view controller is of type UIViewController. There is no UINavigationController in the hierarchy.
• the bar is laid out programmatically using the fluent constraint API as shown below. Note: one potential point of concern is that the height is not explicitly set.
• this answer seems to indicate that UISearchController possesses subtle behaviors which do not play well with auto layout. this answer prescribes using a placeholder view to wrap the searchBar. still, it is unclear precisely what is the appropriate remediation: https://stackoverflow.com/a/35231501/13538737

The code is implemented exactly as shown here:

class RootViewController: UIViewController {
    let search: UISearchController = {
        let x = UISearchController(searchResultsController: nil)
        x.searchBar.placeholder = "Search Ingredients"
        x.searchBar.autocapitalizationType = .none
        x.searchBar.autocorrectionType = .no
        x.searchBar.translatesAutoresizingMaskIntoConstraints = false
        return x
    }()

    var bar: UIView {
        return search.searchBar
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = .brown
        view.addSubview(bar)
    }

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()

        let guide = view.safeAreaLayoutGuide

        bar.topAnchor.constraint(equalTo: guide.topAnchor).isActive = true
        bar.leadingAnchor.constraint(equalTo: guide.leadingAnchor).isActive = true
        bar.trailingAnchor.constraint(equalTo: guide.trailingAnchor).isActive = true
    }
}

The RootViewController is added to the top-level hierarchy as follows:

class SceneDelegate: UIResponder, UIWindowSceneDelegate {
    var window: UIWindow?
    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        if let windowScene = scene as? UIWindowScene {
            let window = UIWindow(windowScene: windowScene)
            window.rootViewController = RootViewController()
            self.window = window
            window.makeKeyAndVisible()
        }
    }
}

Here is a GIF demonstrating the visual defect: