Well, this is something I wish they would make optional on a per game basis. In some games, AF leads to "oversharped" images (at least IMHO). E.g. on PC I turn driver AF off, if the game does not set it by itself, because often it leads to that look. I often like the "developers" perspective on the games more. Yes I know it is no sharping-filter or something like that, but the textures get much clearer which make the image much more sharp.
But well in other games, it can really make a big difference (e.g. Mass Effect, xb360 -> xb1 it was a huge step).
it drops only under very specific circumstances. Most of the game is just 4k60.
But I really don't know why the difference between PS5 and SX is so big. Doesn't make a lot of sense.
Shouldn't be the CPU (that needs some more power) because on the old consoles, the cpu can reach >40fps. So the step to 60 should be minimal and no problem from the power targets perspective.
Another thing that comes to my mind is, that it might a BC game, because it directly supports starting part 1 & 2.