I think it makes sense to remove this button. In the past there was a second button next to it so it allowed to switch between the active route and the draft route. At the moment it shows the button in purple to indicate it is the active route, and yellow when a route changes is being drafted. 

But in that latter case there are also two buttons "cancel changes" and "confirm changes" visible, so it is clear it is the draft route for which details are currently shown. I will remove that top left button in the upcoming version.

Actually I think this button could be used to cancel a DiredtTO , and replace it with the original route.

I found no easy way to go back to the original plan