FYI - Facebook has been using contact information that users explicitly provided for security purposes—or that users never provided at all—for targeted advertising.

(and)
Facebook is also grabbing your contact information from your friends
This means that, even if you never directly handed a particular phone number over to Facebook, advertisers may nevertheless be able to associate it with your account based on your friends’ phone books

https://www.eff.org/deeplinks/2018/09/you-gave-facebook-your-number-security-they-used-it-ads