This thing where Facebook collects a lot of data in ways to which most people would object for years and years, and then when they get caught they claim it was a "bug", is getting really old.
To make matters worse, they usually tend to re-introduce the "bug" as some kind of feature a few years later, as their way of saying "yes, we really do thing our users are that stupid to not realize what we've done, why do you ask?!"