Orion 0.99.127.3.4-rc introduced a button in the URL bar that suggests that the site can be installed as a separate app. 
Unfortunately there currently is no way to toggle showing that symbol. It makes the URL bar unnecessarily crowded, especially on compact tabs, as can be seen in the picture above. It also serves little purpose after the user has discovered it and decided that they do not want to install, e.g., YouTube or reddit as an app. It should remain enabled by default to make finding the webapp feature easier to discover.
The toggle should be located in the toolbar settings:
