Tab bar items not showing up until clicked

I am trying to create a tab bar controller with a navigation controller. I am trying to achieve this programmatically.

Here's the willConnectTo method in my Scene delegate:

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
    // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
    // If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
    // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
    guard let windowScene = (scene as? UIWindowScene) else { return }
    let window = UIWindow(windowScene: windowScene)
    
    // Create the tab bar controller
    let tabBarController = UITabBarController()
    
    let vc1 = UINavigationController(rootViewController: MoviesScreen())
    let vc2 = UINavigationController(rootViewController: FavouritesScreen())
    
    vc1.tabBarItem.image = UIImage(systemName: "film")
    vc1.tabBarItem.selectedImage = UIImage(systemName: "film.fill")
    
    vc2.tabBarItem.image = UIImage(systemName: "heart")
    vc2.tabBarItem.selectedImage = UIImage(systemName: "heart.fill")
    
    tabBarController.setViewControllers([vc1, vc2], animated: false)
    
    window.rootViewController = tabBarController
    self.window = window
    window.makeKeyAndVisible()
}

And here are the 2 view controllers:

class MoviesScreen: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
    
        title = "Movies"
        view.backgroundColor = .red
    }

}

class FavouritesScreen: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
    
        title = "Favourites"
        view.backgroundColor = .yellow
    }
}

The screenshot below shows what the app looks like when I run it:

But when I click on the tab bar item, the item shows up:

As you can see in the first screenshot, the second tab bar item is not visible. I tried the existing fixes I could find on the internet but no luck.