In the dataset, there’s apparently a lot of information that you might not want floating around the internet — including birthdays, locations, full names, and phone numbers — so it’s disappointing to hear that Facebook doesn’t plan to notify users that might be affected.
The company cited two reasons to Reuters as to why it’s not telling users proactively: it says it’s not confident it would know which users would need to be notified, and that users wouldn’t be able to do anything about the data being online.
Facebook Wrote on its blog that it “believes” the data was scraped via its contact importer sometime before September 2019, a method that’s in violation of the company’s policies. But as BuzzFeed News reporter Ryan Mac points out, this doesn’t quite mesh with the fact that the company hasn't spoken out or filed lawsuits against controversial surveillance company Clearview AI for scraping photos from Instagram and Facebook.
Read more at : https://www.theverge.com/2021/4/7/22372707/facebook-responds-533-million-data-leak-notify-users