It’s on their UHD channel as well does that mean world feed is now 4k?
It has been available that way for some time (probably a special request / requiring an extra circuit booking) - at least for those matches shown live in the UK. For instance DirecTV and FuboTV have offered some matches in UHD in the US.
There was at least one foreign broadcaster advertising matches being available in UHD around the same time Sky began to show them. Some posters on another forum misread the translation and assumed it meant all of them, a more careful reading showed that it was selected matches.
Not sure if the games only shown as highlights in the U.K. are covered in UHD yet.