Does Facebook record our conversations? It records everything else

With all the outrage and soul-searching over Facebook's data-mining practices going on at the moment, there has also been a resurgence of some of the other conspiracy theories that have been dogging the service for some years now.
One of these is the idea that Facebook (possibly along with other other social media/internet platforms like Google and Uber) is listening in to, and even recording, our conversations and phone calls, and using them to target its advertising. There are endless anecdotes out there of specific verbal convsersations - at the water cooler, at home, in the supermarket - triggering Facebook ads, despite there being no other way for the service to have gleaned the person's interest in a subject. So, for example, ads about adopting cats suddenly appear after a single offline conversation with a friend on the subject. It's spooky and it's inexplicable.
Apparently, Facebook does have the ability to record conversations (even if it requires specific preference settings), and its voice recognition software, while not infallible, is probably adequate to be able to identify conversation subjects. But Facebook has repeatedly and publicly denied using such a facility for advertising purposes, and some commentators argue that it would just not be efficient and cost-effective for it to do so.
How, then, to explain the many anecdotal examples that seem to indicate that Facebook is recording, or at least listening to our conversations, either through a computer microphone or, more likely, a cellphone? The usual argument is that it has accumulated so much data about our preference, tastes and movements that it just doesn't NEED to listen to us, and it can target ads with such accuracy that it knows the kinds of things we are likely top talk about. So, when we do actually talk about them, we tend to notice the timely advertising (which would have appeared anyway, whether or not we had that conversation).
The other thing I found out recently, which kind of blew me away, is that Facebook apparently records the keystrokes of posts and messages that we never send, and adds that to its ongoing database of information about us, which strikes me as a bit underhand and unfair somehow.
Well, the jury is still out on the extent to which Facebook spies and pries, but the very idea of a computer program that knows us that intimately is a scary thing in itself. Personally, I haven't used Facebook for over 10 years, and even then only sporadically and for specific purposes, so I never really became hooked. I am now considering myself as way ahead of the #DeleteFacebook curve.