This is exactly what what they did here.

That said, the attention of the blog post seems to have triggered them to disclose now on the Apple [1] and Google Play [2] store that they are indeed collecting your location data. They got away with lying for quite some time, over 100k downloads on Play store and 1.57k reviews.

[1] https://apps.apple.com/au/app/battery-monitor-bm2/id11154920...

[2] https://play.google.com/store/apps/datasafety?id=com.dc.batt...