Facebook has taken action against another group of researchers investigating it, drawing more scrutiny and condemnation.

Facebook made headlines when it banned researchers from New York University who were studying political ads and misinformation on the platform. The move was blasted by none other than the FTC’s Acting Director of the Bureau of Consumer Protection.

It appears the NYU researchers weren’t the first groups of researchers Facebook took action against. AlgorithmWatch was studying Instagram’s algorithm, to better understand how it prioritized photos and videos. Like the NYU researchers, AlgorithmWatch used a browser plug-in volunteers installed to collect data from their own feeds.

Evidently, Facebook took issue with the researchers and their work, at first dismissing it as flawed before threatening them. 

AlgorithmWatch said the move shows Facebook’s real intentions.

We designed our add-on with great care so that Facebook cannot identify and prosecute our volunteers. However, Facebook’s reaction shows that any organization that attempts to shed light on one of their algorithms is under constant threat of being sued. Given that Facebook’s Terms of Service can be updated at their discretion (with 30 days’ notice), the company could forbid any ongoing analysis that aims at increasing transparency, simply by changing its Terms.

It’s a safe bet Facebook has only just begun to experience backlash from this latest revelation.