GADRewardedAd object is not destroyed and causes memory leak

[mustafayd]

I created a game, that includes Admob, with Unity for iOS but rewarded ad causes memory leak with current API when I test the game in real device. Since RewardedAd is a one-time-use object so we create the object many times in app lifecycle. However, the rewarded ad object has no Destroy object and it can not be destroyed. I create rewarded ad object in Start function as suggested but this causes object creation in each game level (scene) and it is not destroyed somehow. I played the game for a while and checked the memory in XCode, there are 22 GADRewardedAd object instance.

I also try to unbind all the listeners before new object creation and in 'onDestory function' but nothing changes.

Unity version: 2018.4.01f and 2019.4.17f1
iOS 14.3
Xcode 12.3
Latest Admob SDK