Google seems to either be testing a new UI design for the app search results in the Play Store, or slowly rolling out the new look via server side change, as at least one user has reported seeing this new design for apps when they search for them within the Play Store on their device. The new visual involves searching for apps in the Play Store, and once you tap on a result in the list it opens up in this new card-style view that spans almost the size of the screen, as opposed to taking up the whole screen which is what most users are currently seeing. What's more is that the new design also includes other cards from the search results list and users cycle through them with a swipe to the left or right of the screen.
Google hasn't completely done away with the full screen view for apps when you search for them, of course, as it appears you can scroll down on any of the cards and this expands the card into a full screen view of the app's description and other details, looking the same as it normally does when viewing any other application in the Play Store right now. This is also in addition to the other new layout tweaks that Google is already rolling out to users that changes other parts of the Play Store's design, such as the new, larger install button that shows up when entering an app page, and the deeper color of green that's being used throughout.
Since it's unclear if Google is simply testing the new design or actually rolling it out to users, there's no way of knowing whether or not the new card layout for app search results will appear for everyone. At least one person in the comments on the post from the source indicates that they had seen this new design themselves but that it also disappeared after a day, which suggests that this may be a test to see how users respond or interact with the Play Store and how often they use the search feature. Whatever the case may be, if you search for apps often enough, the new card style layout for the search results is no doubt more appealing.