Only public profile data was leaked, and your phone number if you've enabled looking up your profile by phone number. Facebook's privacy checkup flow will walk you through these settings: https://www.facebook.com/privacy/checkup
I'm pretty sure everybody was 'opted-in' to this feature by default. Afaik I have never actively enabled it and yet I'm in the leak. I provided FB my phone number for 2FA purposes. I'm dumbfounded if they actually allowed people to look up my profile with my 2FA info.
Every privacy offending feature on FB is 100% by default opt-out. This is their ethos. When you gave them your number, you gave them a way to not only permanently & consistenly identify you but also let others "discover" you/r profile aka reason for this leak. Using your number as 2FA auth is just a side bonus.
> Every privacy offending feature on FB is 100% by default opt-out
Uh, what?
To clarify: my reading of the parent posting was that "by default opt-out" meaning the user is opted-out by default, which is contrary to my understanding privacy-eroding features of Facebook are turned-on (i.e. "default to opt-in").
^ Yeah, this in its own is almost as big a scandal as the breach per se. Just what the f.