Apparently there isn't a whole lot of difference between buying the PS4 version of the Tsushima expansion and playing on PS5 via BC vs getting the PS5 native version. Like checkerboarding to 4k instead of 1800p, and faster load times. Though load times are already really fast on PS5 playing the PS4 version through BC. And the cutscenes are rendered in real time now so the animation matches the voices if you're playing in Japanese. Kind of doesn't seem worth the $10 upgrade tbh, might as well just buy the $20 PS4 DLC and play through BC.