Next time you do a search on your mobile device, you may notice something different about how the results are given to you. Google is going to have AMP trump App URLs in their mobile search results. This means that if a website has both AMP URLs enabled, as well as an available app with Firebase App Indexing (formerly Google App Indexing), Google will show the AMP URL over the deep link to the page within your app. It won’t matter if the app is downloaded to your device.
This information was posted by Google in their data anomalies page, where they wrote:
Search results on mobile devices have begun to direct users to the equivalent AMP page, in preference to the equivalent app or web page. This might result in a decrease of traffic to your app pages when an equivalent AMP page exists.
John Mueller from Google confirmed this on Twitter by saying, “Yes, at the moment if an AMP exists for a given URL then we will send the user to that AMP not the deep link.”
— John Mueller (@JohnMu) September 21, 2016
Because AMP is now rolling out to the core Google mobile search results, a user will be taken to the AMP URL instead.