Typing internet://debug in Samsung Internet’s address bar (if debug mode enabled) can show recent referrer logs.
The most common origin for this specific URL string is the Samsung application. Smart Switch is the tool used to transfer data (contacts, photos, apps) from an old phone to a new Samsung phone.
In practice, the actual visited URL would have been: https://r.internet.apps.samsung.com with a referrer from http://www.facebook.com (or more likely https://www.facebook.com ).