On my system, Vivaldi cannot navigate Facebook
Every time I try to open FaceBook the page opens but shows a never-ending loading circle related to a frame that never fills in at the right top corner of the page. In addition, all controls freeze and there is no interaction between keyboard or mouse and the UI/page. If I open facebook in another browser, it asks for permission to run a app "viewtiff" or some such. I don't permit it. Nonetheless, facebook thereafter works in that other browser. Vivaldi is failing to display the request to run this app, and so it just freezes.