The QR code scanning is no longer hung off of search. To scan QR codes you need to access the Bing Vision lens. How do you access Bing Vision Lens? It turns our that lenses are associated with the camera, so following the steps below will work give you access to the Bing Vision Lens.
To search by scanning a QR Code
1. Press the Camera Camera button button on your phone, then tap Lens > Bing Vision Bing Vision.
2. Scan the QR Code by pointing your phone at it.