Toggle favorite is a new feature added to the application. It allows users to mark each album as a favorite by clicking on it. There's a new icon added to each album, next to the title, that indicates if the album is marked as favorite or not (filled image is favorite, empty image is not).
Nowadays it is only possible to mark an album as a favorite, but they aren't yet searchable. An evolution that could add more value to the user is to improve filters regarding favorites/non-favorites albums.