If you log in using Facebook through your Facebook account, you need to change your login method from now on. Microsoft officials today issued a statement saying they will stop supporting this feature in January 2018.
Obviously, the company prefers users to log in through Microsoft accounts, and they can experience many company services such as Office 365, Xbox Live and so on. In fact, the number of users who can log in to Facebook using Facebook is not too large at present. Therefore, users can only log in to the desktop and web pages, and all mobile and Windows clients cannot log in.
Reference: Skype