I'm sure there's a lot of actual data sharing going on, but I also wonder how often these are just the Baader-Meinhof effect (noticing recently mentioned things everywhere).

Today I made an insta post about sand that resembled dunes at the beach, mentioning a camel in the description. Less than 5 minutes later I saw the camel logo at the beach bathroom, on someone's discarded cigarettes.

Here it's obvious that there is no connection. But if I had instead randomly seen a camel cigarette ad online at that point in time, I might have seriously wondered if it's because I mentioned it in the post.