Hi @tay!
The link is one of the partner bookmarks (see the little icon in front?) that the browser comes with. You must have seen them on the Speed Dial and you can find them all in the Bookmarks Panel.
As you type in the Address Field, in addition to history, you get suggestions from bookmarks as well.
You can read about partner bookmarks here: https://vivaldi.com/blog/vivaldi-business-model/.