https://arstechnica.com/information-technology/2019/08/google-play-apps-with-1-5-million-downloads-drained-batteries-and-slowed-devices/

Researchers have discovered two Google Play apps with more than 1.5 million downloads engaging in a new form of click fraud that drained batteries, slowed performance, and increased mobile data usage of infected phones.

The apps—a notepad app called Idea Note: OCR Text Scanner, GTD, Color Notes and a fitness app with the title Beauty Fitness: daily workout, best HIIT coach—carried out the stealthy form of fraud for almost a year until it was discovered by researchers at security firm Symantec. Google removed them from Play after receiving a private report.