When you’re sent a URL/link through a 3rd party and it’s clicked, Asana opens up through the browser and if you have the app installed, prompts you to open the app. The landing page is a single-task view with no menu bar on the left side. The only way to get back to a page with the menu options is to click the x to close the window in the upper righthand corner. It would be helpful to go to wherever that task lives more easily or, better yet, to be able to navigate to any other project by having the left side menu bar available or buttons to take you home or to your My Tasks.
I think this should go in the upper lefthand corner of the screen since that is where the menu bar and to go back, tasks and projects are always located on the left.