Google Admob Interstitial shows the following error "The provided view controller is not being presented" in SwiftUI

Question

I followed one of the tutorial and tried to use a button to show interstitial ad in my SwiftUI app but it keeps showing this error in logs.

What exactly is the fix since Admob tutorial for SwiftUI is extremely limited at the moment?

I have hooked it up to a button in content view and it refuses to show the ad...

final class InterstitialAd: NSObject {
    var interstitialAd: GADInterstitialAd?
    
    static let shared = InterstitialAd()
    
    func loadAd(withAdUnitId id: String) {
        let req = GADRequest()
        GADInterstitialAd.load(withAdUnitID: id, request: req) { interstitialAd, err in
            if let err = err {
                print("Failed to load ad with error: \(err)")
                return
            }
            
            self.interstitialAd = interstitialAd
        }
    }
}

final class InterstitialAdView: NSObject, UIViewControllerRepresentable, GADFullScreenContentDelegate {
    
    //Here's the Ad Object we just created
    let interstitialAd = InterstitialAd.shared.interstitialAd
    @Binding var isPresented: Bool
    var adUnitId: String
    
    init(isPresented: Binding<Bool>, adUnitId: String) {
        self._isPresented = isPresented
        self.adUnitId = adUnitId
        super.init()
        
        interstitialAd?.fullScreenContentDelegate = self //Set this view as the delegate for the ad
    }
    
    //Make's a SwiftUI View from a UIViewController
    func makeUIViewController(context: Context) -> UIViewController {
        let view = UIViewController()
        
        //Show the ad after a slight delay to ensure the ad is loaded and ready to present
        DispatchQueue.main.asyncAfter(deadline: .now() + .milliseconds(1)) {
            self.showAd(from: view)
        }
        
        return view
    }

    func updateUIViewController(_ uiViewController: UIViewController, context: Context) {
        
    }
    
    //Presents the ad if it can, otherwise dismisses so the user's experience is not interrupted
    func showAd(from root: UIViewController) {
        
        if let ad = interstitialAd {
            ad.present(fromRootViewController: root)
        } else {
            print("Ad not ready")
            self.isPresented.toggle()
        }
    }
    
    func adDidDismissFullScreenContent(_ ad: GADFullScreenPresentingAd) {
        //Prepares another ad for the next time view presented
        InterstitialAd.shared.loadAd(withAdUnitId: "ca-app-pub-3940256099942544/4411468910")
        
        //Dismisses the view once ad dismissed
        isPresented.toggle()
    }
    
    func ad(_ ad: GADFullScreenPresentingAd, didFailToPresentFullScreenContentWithError error: Error) {
        print(error.localizedDescription)
    }
}

struct FullScreenModifier<Parent: View>: View {
    @Binding var isPresented: Bool
    @State var adType: AdType
    
    //Select adType
    enum AdType {
        case interstitial
        case rewarded
    }
    
    var rewardFunc: () -> Void
    var adUnitId: String
  
    //The parent is the view that you are presenting over
    //Think of this as your presenting view controller
    var parent: Parent
    
    var body: some View {
        ZStack {
            parent
            
            if isPresented {
                EmptyView()
                    .edgesIgnoringSafeArea(.all)
                
                if adType == .rewarded {
                    
                } else if adType == .interstitial {
                    InterstitialAdView(isPresented: $isPresented, adUnitId: adUnitId)
                }
            }
        }
        .onAppear {
            //Initialize the ads as soon as the view appears
            if adType == .rewarded {
                
            } else if adType == .interstitial {
                InterstitialAd.shared.loadAd(withAdUnitId: adUnitId)
            }
        }
    }
}

extension View {
    public func presentRewardedAd(isPresented: Binding<Bool>, adUnitId: String, rewardFunc: @escaping (() -> Void)) -> some View {
        FullScreenModifier(isPresented: isPresented, adType: .rewarded, rewardFunc: rewardFunc, adUnitId: adUnitId, parent: self)
    }
    
    public func presentInterstitialAd(isPresented: Binding<Bool>, adUnitId: String) -> some View {
        FullScreenModifier(isPresented: isPresented, adType: .interstitial, rewardFunc: {}, adUnitId: adUnitId, parent: self)
    }
}