Any app that uses Facebook SDK, of which there are thousands. Zoom only removed it in March 2020, after it was raised as a privacy issue. they are a massive, publicly traded company, and they were fine with keeping it in their codebase, until enough people complained.
Anyone who advertises with FB sticks the FB pixel SDK in their app to track conversions and performance of their FB ad spend. This pixel tracks a lot and reports back to FB.
For example?