i don’t know if it’s just because i’ve gotten so used to playing with the input lag but it feels significantly faster after this update. One thing i noticed is that the v-sync setting doesn’t work but i can confirm that the input delay issue has been fixed though i’m not too sure whether this is what it felt like before the december update.
I think the recent conversation around input lag on Xbox stems from the 120 fps issue, and not any standalone input lag being introduced in a recent update. If you lose half of the frames you normally play with (going from 120 to 60), the game will feel a lot slower, and your inputs will feel slower. With 120 fps support now restored, that input lag-like feeling should be gone.
Anecdotally, I just played a few matches on my own Xbox Series X. Playing with 120 fps again, and I'm not experiencing any input lag. (I can also see the HDR settings in the game, so I can confirm for folks in the comments that those settings didn't go anywhere.)