That was photo-shopped or someone used a hot tool to spell that out on the tire. I don’t thin there is any way to mold that into the tread (@CapriRacer weight in, please) to appear later.
Notice the wear bars are still visible and are not at the same level as the tread. That means they are still legal to drive on. They ARE wearing funny as the shoulder at the top of the page is worn smooth.