You could track cookies. But at this point, I expect it. Amazon searches showing up in FB are usually local — from your computer through an iframe.
But that aws ad looks like keyword driven and part of FB’s database on you.
I embrace it now. I’m watching my Instagram (which I use differently) just starting to modify my FB ads. (they’re already linked but the percolation is a bit slower)
In your case, I think it might be “wow, I just got a blue car and now EVERYBODY’S got blue cars”.
It’s Salient. Were you talking about AWS at any point between a few weeks ago and today? Why didn’t ads show up then?
But I could be wrong of course. I giggle when I’m talking about something and five mins later it’s showing up on FB.
I know their Amazon trick at least. If you logout of Amazon, suddenly you won’t see your latest searches from Amazon on Facebook ads.
So that’s how I know it’s a direct iframe, based on you being logged in, but no information is actually passing to FB in that instance.
But I don’t know if it qualifies in this case.