I use Facebook for some hobby groups, and I only use Safari to view it.. the other day my daughter and I were watching The Fast and the Furious movie and I started getting my feed full of all the cars from the movie.. so we did some experiments saying words like KFC and beer while the screen was opened, and we started getting beer and KFC ads in the feed.. i dont know if the app makes it worse, but it was certainly a bit of an eye opener
iPhone unlocked with Facebook opened in the safari browser (no meta apps installed, and the only two apps approved to user the microphone in the security settings are Teams and my Banking app for voice security prompt). We were watching Fast and the Furious on the TV in the loungeroom and we were noticing videos pop up on Facebook on the phone for Honda Civics, then Toyota Supras etc. We then started joking talking about KFC and beer as a test, and within 10 minutes we successfully started seeing ads for Beer, KFC. We then tried another when we started talking about Bryan Adams tickets, and sure enough, we got an ad to buy tickets to Bryan Adams. It would take about 10mins from talking about a topic to things about that topic to start appearing in the feed