My spouse used TikTok for a while on the app. I can’t remember if they logged in or not (I never used it), but the videos it recommended where kinda shocking. It would recommend reviews of a fridge we had bought, but hadn’t explicitly searched for on TikTok, or anywhere else that I recall. There were also some other coincidental videos that would pop up that just seemed eerie. I assume there’s some data broker TikTok uses (AAID or IDFA tokens perhaps for fingerprinting). Needless to say, we stopped using it and I don’t open shared links anymore.