I think the whole thing is absolutely terrifying.
If we were literally smack in the middle of the Sahara Desert, no humans apart from us on here for hundreds of miles, we had no electronic devices of any sort, nattering about our bodies and their functions, you can guarantee that 721 miles away there'll be FB ads for period products and bum lifts coming up on our FB feeds!
You only have to THINK ''I want to buy a red car'', and there are immediately adverts all over social media and emails about them. That happened to me a few days ago when I was in my own bedroom at home, completely alone, about 10 pm, and I thought ''I need to buy a new bedside table lamp''. I didn't even say it out loud, just in my mind, and I didn't even have my ''spying'' mobile in the room, but when I checked my mobile about 4 hours later, which was in my home office, there were tons of adverts for bedroom table lamps.....
Give me alien implants any day over creepy brain spying tech!