The last monitoring attempt that I heard of used a browser plugin to scrape the user's posts. The point was to monitor political parties and their ad targeting

The last monitoring attempt that I heard of used a browser plugin to scrape the user's posts. The point was to monitor political parties and their ad targeting before the upcoming elections in Germany. Generally, Facebook needs to view contents of posts that is able to access third party websites a severe bug. It is an unwelcome data leak at least and a true attack vector at worst. So, tracking by linking to a third party tracking pixel should be impossible.