Shoshana Wodinsky, writing at Gizmodo:
A series of Instagram ads run by the privacy-positive platform Signal got the messaging app booted from the former’s ad platform, according to a blog post Signal published on Tuesday. The ads were meant to show users the bevy of data that Instagram and its parent company Facebook collects on users, by… targeting those users using Instagram’s own adtech tools.
The actual idea behind the ad campaign is pretty simple. Because Instagram and Facebook share the same ad platform, any data that gets hoovered up while you’re scrolling your Insta or Facebook feeds gets fed into the same cesspool of data, which can be used to target you on either platform later.