Is it the most obvious answer? 20 years ago, I drank a glass of milk and watched the X Files, and then there was an advertisement for milk. Is the most obvious answer that my TV was watching me?
The precision is what makes it seem weird, and without an understanding of how a company would target ads to you, the idea that you're being literally listened to by the app, seems possible.
> Attributing them to spying is a ticket to a level of paranoia that some people have a very hard time finding their way back from.
I'll state again that I don't believe FB is actually listening in on phone conversations, but to the majority of their users, they may as well be doing just that. It is all just spying, only using different sources.
Today, the advertisements aren't about milk, but are about obscure products that eerily match private conversations.
Facebook makes a business of watching you.
If it's legal for FB to use the mic while you're not perfectly aware, they will do it. That said, I don't believe they are doing that, but they are using basically every aggressive means available to capture information about you, which they own, and will do as they please with.