Problem with interstitial Google ads on Android

My problem: When i leave the Android app while a interstitial ad is showing, the app becomes unresponsive when i return to it. App freezes when i try to close the ad.
Any idea what might be the cause? Have you been able to use interstitial Google ads in your game?

Video showing the error:

logcat: 2021-02-09 23:08:29.815 2042-2061/? I/system_server: Explicit concurrent copying - Pastebin.com
java code: package com.blueskied.mobileads;import android.content.Context;import andr - Pastebin.com