Now we can basically say that its not Facebook and Google doing this directly, its our televisions and appliances that are listening and just selling that data back to the ad-networks.
In this case Meta, Google etc can honestly say they aren't surrepticiously listinging to you or collecting data not in their privacy statement. They just buy it instead.
So I need to write a chaffing agent that runs when I am not home and randomly spouts synthetic conversations through non-smart speakers about nappies (kids a re long gone), nuclear weapons development, plumbing, union membership, crochet, video games, crypto coins, and other things we don't normally do.
Finding out that TVs are listening does not mean Google and Facebook aren't. I've had plenty of times in an old car, or on a walk talking about something only to have related ads pop up later.
Most people are not that unique. They know where you are and who you are with and any searching or sites you have been to and what is in your text messages or whatsapp as well as that same information for all the people 6 degrees away from you. They know people like you, who are your age and like the things you like and are where you are with friends like yours etc etc it goes on and on.
People rarely talk about things unprompted and you will only notice when you think you talked about something and then see an ad for it so there is a confirmation bias as well.
VoIP has been around for 25 years. Compressed audio is a tiny amount of packets. It doesn't need HD audio, it just needs enough to recognize words. Enterprise VoIP only needed a 128kb connection 25 years ago to work. On a smartphone, 128kb is nothing and will blend in with background connections. Facebook could record and monitor your audio 24/7 and it won't even be a blip in the network traffic, especially if it does a quick process of the audio before sending it to Facebook.