This is undeniable some of the App developers experience in sudden dropped of their earnings from Google Adsense. Here are some of the common things why your earning dropped and how to fix it?
Remember, this is just a general way to increase and optimize your app performance. Google always updates and change its algorithm, as an indie app developer, it is necessary for you to stay updated on Google Updates and do more research to improve your apps
Hope this information might benefit you. Good luck and all the best.