It does seem that Google has been embracing quite a few design changes of late. Of course, Google never has been shy about introducing changes to the way many of its apps look, feel and operate. Recently though, and largely in part thanks to the release of the Pixel and the Pixel XL, those changes have been coming much thicker and much faster. One prime example is the actual Pixel Launcher which comes as standard with the two new Pixel phones. Among other things, the Pixel Launcher includes a pull-up to access app drawer and a new pill-shaped Google search shortcut. The last one in particular, is quite the change from the standard and elongated Google Search bar that can be found on most, if not all, Android devices. However, in spite of being very different, it does seem as though Google is in the process of testing a new design for that longer and more commonly-encountered Google Search widget.
As you can see from the image below, courtesy of Android Police, the new look Search bar is one which adopts the same sort of length as its predecessor, but is significantly different in shape, style and design. The first and most obvious difference is that the new look adopts a much more circular, or tubular, design and loses most of the squareness that you will find with the older look (shown above). In addition, gone is the actual full length Google name and instead, the new designed adopts the multi-colored G icon which Google has been using more often of late, with the likes of the Google App and the Pixel Launcher Search pill. In fact, in many ways, this new design does look very much like the Pixel pill, albeit, significantly longer. One of the aspects which has remained in the new design though, is the inclusion of the mic icon which can still be found at the very right of the Search bar, like before.
At the moment, it is not known as to whether this new design will be rolling out to all users anytime soon. It does seem to be the case that some users are reporting they have received the new design on their devices, so there is a chance that it will arrive on other devices soon. Although as mentioned, there are no firm confirmations on this as of yet.