The SSD is most definitely not the reason why this game has popin - the game is probably far too high res for the XSX GPU to handle lots of transparent textures on screen at the same time, or too high res for it to be shading so many triangles on screen at the same time. The game targetting 4K is murdering its visuals probably.You can test this in many open world games that came out this gen - on PC if you turn up the vegetation and draw distance on PC with competent CPUs at 4K, you immediately are hit with a wall of GPU performance when you enter forests: check out Red Dead Redemption 2, GTA V, or Watch Dogs 2 outside of San Fransisco near the woods.