Google Ads BannerView persists across scenes

If you're using the AdMob plugin from Prime31 you should do something like this

 public class AdsController : MonoBehaviour {
     public static AdsController Instance;
 
     void Awake() {
         if (Instance == null) {
             Instance = this;
             DontDestroyOnLoad (this.gameObject);
         }
         else
             Destroy (this.gameObject);
     }
 
     void OnEnable() {
         AdMobAndroidManager.receivedAdEvent += receivedAdEvent;
     }
 
     void OnDisable() {
         AdMobAndroidManager.receivedAdEvent -= receivedAdEvent;
     }
 
     public void showAd() {
         AdMobAndroid.createBanner( "test", AdMobAndroidAd.smartBanner, AdMobAdPlacement.BottomCenter );
     }
 
     public void destroyAd() {
         AdMobAndroid.destroyBanner();
     }
 
     void receivedAdEvent() {
         if (Application.loadedLevelName == "Game_Scene")
             destroyAd ();
     }
 }

You should add this script on a gameobject on your first scene. At runtime only 1 instance of the this class will be available in every scene of your project. In your case, the add will be called in your menu scene, if the game scene will be loaded before the ad was showed, in the game scene this script will catch the received ad event, will check if it is game scene and if so it will destroy the banner.

Use this if you want to diplay an ad

 AdsController.Instance.showAd();

If you're using another plugin, you should change "AdMobAndroidManager.receivedAdEvent" with the correspondent received ad event from your plugin.

I hope this helps.