(I know many of you already know it but this incident I experienced made me so paranoid about using smartphones)
To start off, I'm not that deep into privacy rabbit hole but I do as much I can possibly to be private on my phone. But for the rest of phones in my family, I generally don't care because they are not tech savvy and pushing them towards privacy would make their lives hard.
So, the other day I pirated a movie for my family and since it was on Netflix, it was a direct rip with full HD. I was explaining to my family how this looks so good as this is an direct rip off from the Netflix platform, and not a recording of a screening in a cinema hall(camrip). It was a small 2min discussion in my native language with only English words used are record, piracy and Netflix.
Later I walk off and open YouTube, and I see a 2 recommendations pop-up on my homepage, "How to record Netflix shows" & "Why can't you screen record Netflix". THE WHAT NOW. I felt insanely insecure as I was sure never in my life I looked this shit up and it was purely based on those words I just spoke 5min back.
I am pretty secure on my device afaik and pretty sure all the listening happened on other devices in my family. Later that day, I went and saw which all apps had microphone access, moved most of them to Ask everytime and disabled Google app which literally has all the permissions enabled.
Overall a scary and saddening experience as this might be happening to almost everyone and made me feel it the journey I took to privacy-focused, all worth it.
Listening to audio would be the least effective and most expensive method of data collection for advertisers. It's not happening. They already have literally over a million data points on you, there's nothing useful for them to glean from your audio that they don't already have ad nauseum.
You see thousands of ads and recommendations every day. You finally found one that was relevant to you. It's not that deep.