Comment by weikju

It's the in-app browser. The one that opens within the app, so that people don't need to switch to another app, and usually used for short-lived sessions. It doesn't modify or spy on the actual separate browser (Safari etc), just on whatever happens inside the app (as you would expect, app knows what's going on within itself), and it just so happens that sometimes in the app there is a browser page being displayed, which then goes to reason can also be spied on.

Android has these in-app browsers too, they may or may not be subject to this.