https://www.techdirt.com/articles/20201024/02131045571/facebooks-threat-to-nyu-researchers-is-mistake-inevitable-follow-to-overreaction-to-cambridge-analytica.shtml

Late on Friday news came out that Facebook had sent a cease and desist letter to researchers at NYU working on the Ad Observatory project. At issue was that the project had asked people to install a browser extension that would share data back to NYU regarding what ads they saw. Facebook -- responding to significant criticism -- has put forth an ad library that allows researchers to search through what ads are being shown on Facebook and who is behind them (which is good transparency!), but it does not show how those ads were targeted. This is what the researchers at NYU were trying to collect data on. And that is a reasonable research goal.

Facebook has argued that this is a breach of Facebook's terms of service -- though it does seem notable that this is coming out right around the same time that these very same researchers discovered that Facebook's promise to properly label political ads isn't working so great (it's a tangent, but this is why promising to label political ads may be problematic in the first place: you're going to miss a bunch, especially on a platform this big).