Engine is probably a big issue, yea. Wouldn't really say it's 'unoptimized' in light of that, they're probably squeezing all they can out of it, and getting some at least pretty good results. FFXVI looks amazing in certain respects, and then lackluster in others. Fairly mixed big, but still fairly clearly next gen on the whole.
And like most next gen games, it is going to require reconstruction to run well. I think even on PS5, it was running FSR1. I feel like cross-gen lasted so long that people still haven't mentally adjusted to the fact that actual next gen games were gonna be heavy. It was inevitable.
