Is it not BT Sport Ultimate now? Im guessing they dropped the UHD moniker as they are broadcasting around 2.5K rather than 4K. I believe they make more reference to the channels HDR capabilities these days which is more to do with colour and contrast rather than resoloution. BT Sport has UHD capabilities but only through specific apps.
If BT are still using the UHD moniker then its akin to them also using "fibre" to describe VDSL broadband