It's not only Facebook, BTW. Whenever you provide those "additional details" to "secure" your account, be sure there's a high probability they will be used elsewhere.
In my case, I provided a personal email address to Azure as an alternative email. That email address had an Azure account associated with it. Microsoft merged the two accounts without me asking for it and (not very surprising) it caused some issues displaying the subscriptions properly to the point that their support asked me to create an empty subscription with a brand new email address.
It's not only Facebook, BTW. Whenever you provide those "additional details" to "secure" your account, be sure there's a high probability they will be used elsewhere.
In my case, I provided a personal email address to Azure as an alternative email. That email address had an Azure account associated with it. Microsoft merged the two accounts without me asking for it and (not very surprising) it caused some issues displaying the subscriptions properly to the point that their support asked me to create an empty subscription with a brand new email address.