I am using google_mobile_ads package for displaying interstitial ads. On Android user can press back button and close ad without waiting some time. iOS interstitial ads have some earnings but Android haven’t. I think that is the reason. Is it suppose to be like this on Android or am I doing something wrong?

I have developed another app using interstitial ads on this app interstitial ads is not closing after back button. User must wait some time and then close button will appear and they can close with that button. I have checked all versions of the packages related to google_mobile_ads and they are all same.