@AverageAsker Can you try and open the Project property by right clicking the Project > Properties
It will look something like this:

Here, uncheck the Use Shared Runtime and then build your App
See if you are able to deploy it directly and run the App

.

.

.

.

Looking for Free* Microsoft Support on Xamarin Issues, visit https://aka.ms/xamarinsupport

The InterstitialAd class does not come with native event listeners. To implement listeners you must create a class that inherits from AdListner and then define the event listeners.

namespace admobDemo
{
    class adlistener : AdListener
    {
        // Declare the delegate (if using non-generic pattern).
        public delegate void AdLoadedEvent();
        public delegate void AdClosedEvent();
        public delegate void AdOpenedEvent();

        // Declare the event.
        public event AdLoadedEvent AdLoaded;
        public event AdClosedEvent AdClosed;
        public event AdOpenedEvent AdOpened;

        public override void OnAdLoaded()
        {
            if (AdLoaded != null) this.AdLoaded();
            base.OnAdLoaded();
        }
        public override void OnAdClosed()
        {
            if (AdClosed != null) this.AdClosed();
            base.OnAdClosed();
        }
        public override void OnAdOpened()
        {
            if (AdOpened != null) this.AdOpened();
            base.OnAdOpened();
        }
    }
}

Check the tutorial:
https://blog.terrible.dev/admob-with-xamarin-part-2-interstitialad/

Hi, I have tested your code and encountered the same error. After updating Xamarin.Android.Support.Design to 28.0.0.1, it works well.

Add the corresponding click event method in the custom_viewHolder.

public class CarItemRecyclerViewAdapterViewHolder : RecyclerView.ViewHolder
{
    ...

    public CarItemRecyclerViewAdapterViewHolder(View itemView, Action<CarItemRecyclerViewAdapterClickEventArgs> clickListener, Action<CarItemRecyclerViewAdapterClickEventArgs> longClickListener) : base(itemView)
    {
        ...

        //TextView = v;
        itemView.Click += (sender, e) => clickListener(new CarItemRecyclerViewAdapterClickEventArgs { View = itemView, Position = AdapterPosition });
        itemView.LongClick += (sender, e) => longClickListener(new CarItemRecyclerViewAdapterClickEventArgs { View = itemView, Position = AdapterPosition });
    }

    private void clickListener(CarItemRecyclerViewAdapterClickEventArgs args)
    {
        //add the feature code
        Console.WriteLine("====itemView.Click:clickListener");
    }

    private void longClickListener(CarItemRecyclerViewAdapterClickEventArgs args)
    {
        Console.WriteLine("====itemView.Click:longClickListener");
    }
}