I live on the becontree estate, dagenham, essex, uk. On a road called wood lane at a junchion with boxol road, there is a small green area. On this is a apple tree that bears this particular fruit. IT HAS BEEN THERE SINCE THE EARLY 1930,s when this estate was built, if not before when this area was mostly farm land. The apples are good eating but small. You could probably locate the tree usein google earth with info i have given. SO THERE IS NOTHING NEW ABOUT RED FLESHED APPLES !!
Red fleshed apples have been around for, even, longer than that! There are many varieties of red fleshed apples. This article will give you more information on some of the newer varieties: https://www.gardeningknowhow.com/edible/fruits/apples/apples-with-red-flesh.htm