StartActivity start after few seconds when admob interstitial Ad close

In onAdDismissedFullScreenContent of Interstitial Ad start new Activity using startActiviy(Intent(...)) in normal case ad show and close the inter ad the new Activity start normally.

The issue is when Inter Ad show then I press home button and open app again from recents then I press on inter ad close the Ad close but the new Activity start after few seconds why.

here is onAdDismissedFullScreenContent code

 override fun onAdDismissedFullScreenContent() {
        startActivity(new Intent(this, NewActivity.class));
        finish()

}