The deep link in a Marketo email does not redirect to the designated App.
By design in Marketo, when tracking is enabled for a link, the link will be wrapped with a tracking link like 'http://test.website.com/[unique sequence of characters]'. So when a tracked link is clicked, the link 'http://test.website.com/[unique sequence of characters]' is first loaded in a browser then redirects to the actual link in the same browser. Therefore, as some deep link configuration can depend on the actual link first loading, a tracked link in Marketo does not redirect to the App.
One workaround here is to disable Marketo tracking link so that the deep link will redirect to the App. However, the trade-off of this is that the click link activity will not be recorded in Marketo.