A mobile clickfraud campaign used 22 Android apps to trick online advertisers into paying the higher price for advertising on iPhone 5 to 8 Plus devices. The fraudulent apps were games and utilities, favorite categories among Android users. The most popular of them, a flashlight called Sparkle, got over one million installs. One explanation for faking the user-agent string to show an Apple device is that advertising networks pay more on average for ads delivered to this platform than Android. Together, the 22 fraudulent apps caught by Sophos had been installed more than two million times.
Source: https://www.bleepingcomputer.com/news/security/android-clickfraud-op-impersonates-iphones-to-bump-ad-premiums/