Even if it is a bug, just enabling the higher graphics settings on Series X might not be enough to catch Series X up to PS5, enabling those higher graphics settings could potentially lower the framerate on the 120 fps mode to below the framerate on the PS5 120 fps mode, which would take extra optimization time to fix. We'll have to wait and see the test of the patch.
If it is a bug then it should just be a matter of correcting it, if it brings performance to erratic sub 120fps than it is pretty clear it wasn't a bug.
duduspace11 "Well, since we are estimating costs, Pokemon Red/Blue did cost Nintendo about $50m to make back in 1996"
Mr Puggsly: "Hehe, I said good profit. You said big profit. Frankly, not losing money is what I meant by good. Don't get hung up on semantics"
Azzanation: "PS5 wouldn't sold out at launch without scalpers."