Comment by npteljes

Third party in this case could be two things at least.

One, an advertisement that is about something that provided by someone who is not Meta - like a Nike shoe, or a law firm.

Two, third party could imply that the data left the Meta ecosystem - like how if you visit a blog, and there is a Google Adsense banner, then your visitation data left the blog, the first party, to end up at Google, a third party, and possibly others, again, third parties.

I am making this "third party" distinction, because I think that this is a significant step in what it takes to make advertisements "dystopian", which is the premise of the original post. I think that the situation that OP encountered, that he used a service, and then service itself did something unexpected, is not at all dystopian. However, what the title posited, that his face is now used for targeted advertisements, has much more far-reaching implications - like, for example, it could be the next Cambridge Analytica scandal.