Do the following and the ad serving limitation will be removed
1. Delete all the ad-units that are giving you abnormally high request and wait for about a week the ad-serving limitation will be removed.
2. Create a new ad-unit
3. Update your app with the new ad-unit
4. please make sure you do not place the banner ads units request code on all events sheets just the home event sheet will do
Thanks for the 4th point. Maybe I think that it is the culprit in my case
Actually my intention behind implementing banner ads in multiple event sheet is that if it fails to load in one event sheet due to any reason then it will get loaded in another event sheet & I will not lose money
Edit:-
I implement banner ads like this :-
Should it be a problem? Because if ad is already loaded then it will again not load. Otherwise it will load