At least a few years ago, Facebook did publish about partnering with Twitter and Microsoft to build tools for sharing image/content hashes [1], presumably to better aid in removal or prevent dissemination of certain types of content. It's not outlandish to suggest the partnership runs deeper 2-3 years later to cover more vectors.

[1] https://newsroom.fb.com/news/2016/12/partnering-to-help-curb...