Google has done it yet again. Some Chinese developer seems to have violated Google's advertising policies. Therefore, it decided to ban the Chinese developer. Read more at theverge.com
CooTek is the one who has been banned from getting any access to Google's Ad platforms. CooTek seems to have played a pretty smart game and with the help of its plugin BeiTaAd was sending ads to users even while the app was not in use.
Google claims that is has stringent policies related to that of Google Play Store and it cannot stand any kind of malicious activities.