Yes - minimise the app and open it again immediately. Doing so dismisses the interstitial video (AdMob) that did not complete playing at the point of app suspension.
I do (normally!) carefully monitor all the events connected with displaying AdMob ads in the listener. But no, I have not checked the events as a user suspends and resumes. Reason being is that regardless of what happens in the listener (print("event.phase etc etc) the user can still easily circumvent seeing the AdMob ads using a quick suspend/resume.
But you make some good suggestions.
Alas, if I attempt to show an interstitial in “applicationResume” in the OnSystemEvent(event) handler regardlessof flag setting/testing, no interstitial will show (or perhaps I should say continue).
I am sooo tempted to try one of my older (then) Corona apps to see if this problem occurs but dare not test my ads on a live app in case of account suspension.
I wish someone would check this suspend/resume action and see if AdMob (or any other ad provider!) fails to resume playing when a user suspends and resumes while an interstitial video ad is showing.
So annoying!