Is it more efficient to have a whole scene dedicated to the “Game Over” whenever two colliders hit each other? Or is it better to have a transparent UI Image become visible after they collide and everything else is disabled?
Personally I prefer not to use a separate scene. I create a prefab of my GameOver scene and instantiate it when needed.
I would keep it in another scene. But pre-load it beforehand so I can show it quickly.
Having to toggle the visiblity every time you edit is too much hassle and too expensive to maintain.