Earlier quoted context omitted.
The most galling offer we saw on the mobile app side was something that would turn on the user's microphone, and listen for ads on tvs around them to track what they'd been exposed to offline. Adtech is such a thoroughly gross field.
But every time this comes up the threads are flooded with people saying it doesn't actually happen and the ad companies just work out what you're interested in by what you're browsing.
I just did a virtual visit with a doctor that used a video conferencing service that work without an app on iOS and just used Safari. I had to give the page explicit permission to use my microphone