“Once installed on the device, the adware apps wait several weeks before activating their ad-fraud activity to deceive the users and evade detection by Google reviewers.”
McAfee found 43 apps on Google Play with 2.5 million installs loading ads while phones sat idle. They asked users to exempt them from battery saving and pulled their timing from Firebase, Google’s own service. Google removed them only after McAfee reported them. Google’s review process lost to a timer.