I am pretty sure it is the new layout they are going to make everyone use soon. They are doing a slow roll out which is where they select a certain percentage of their users and force them to use it so they can slowly fix bugs that come up before they make it the default layout. If you want to you can try to replace the v3 with www in the url. It might take you back to the old layout, but there is also a chance that as soon as the site loads it will redirect you to the new layout