The third party keyboard apps are a big question for the OP. Another consideration, there are companies that track and sell geolocation data. It's "anonymized"

The third party keyboard apps are a big question for the OP. Another consideration, there are companies that track and sell geolocation data. It's "anonymized" but so precise you know the street address a user resides at. It is not a stretch to consider "anonymized" retargeting from keyboard inputs. I was dismissive of it in the past, as comments voted higher here are. However I've seen enough weird ads show up within minutes of making jokes about obscure topics that I suspect there is something going on. The piece that might be missing here is third parties collecting signals, "anonymizing" them, and then ads get re-displayed through Facebook, Google, etc. It may not be the major ad platforms doing it directly. In theory this should be harder now with the iOS tracking restrictions. For the skeptical, consider Avast's Jumpshot. Here millions of users thought they were protecting themselves when their raw browsing stream was being sold live to third parties. I They aren't the only company that has done that. https://www.theverge.com/2020/1/30/21115326/avast-jumpshot-subsidiary-suspended-data-collection-selling-ceo-blog-post https://www.theverge.com/2020/1/30/21115326/avast-jumpshot-s...