Ad display delayed on Android, displayed immediately on iOS

Hello,

is that normal, that on Android, ads are getting displayed with little (but noticeable delay) however on iOS they are getting displayed straight away, immediately? Lets say we have following scenario,

GAME OVER

DisplayUnityAd();

ReloadLevelScene();

On iOS, on all tries, ad was always displayed immediately, and after ad was closed, level was reloaded.

On Android, in most cases, ad is getting displayed with delay, in many cases showing video ad after level was already reloaded.

(off topic, on another hand, on Android, by using unity's IAPs api, systems confirm purchase appears straigh away on android, yet on ios its often delayed and appears after X seconds, based on reviews from 2 games with over 5.000.000 downloads each)

Would apprecieate if someone got some insights, regards.