Facebook: The phone number specified for 2FA is publicly visible by default
For the 2FA from Facebook you have to enter your telephone number. It has now been announced that this will then be publicly visible by default.
What 2FA, or two-factor authentication, is, I have in this article here explained in detail and adequately. In order to be able to use this on Facebook, you have to provide a phone number for security, according to the platform itself. Facebook took advantage of this last year to place appropriate advertising for individual users. Now it turned out that the number given was originally publicly assigned to one's own Profile is visible.
How can I prevent this?
Fortunately, if you don't want the latter, you can largely deactivate it in the privacy settings. To do this, go to the top right arrow in the web app and select the “Settings” item. In the menu you can see a left sidebar with the option “Privacy”. Almost at the bottom there is an entry that says, "Who can search for you using the phone number you provided?" The "best" thing that can be selected here instead of "everyone" is "friends". And even then, the phone number is visible to a small number of users. Sorry Facebook!
Source: 9to5Mac