Recently i got a mail that
Google is focused on providing a great experience for families on Google Play and wants to help make sure that any ads served to children are appropriate and compliant. Review our ads and monetization policy in the Developer Policy Center.
If your target age groups include children and you want to serve ads to them, you must use one of the ad networks below that have self-certified that they are in compliance with Play’s
ad requirement
Check this link- Google Play certified ad networks program - Play Console Help