The 4090 is several times more powerful than the PS5's GPU and the 5800X3D is far above the PS5's CPU. The fact that the 4090 drops to the 40's is not even comparable. Furthermore, what setting below Very Low are you referring to?
It was a 5800X, not an X3D. Still more powerful than the PS5 of course but without matched settings then I'm not sure what the value of trying to draw conclusions is at this point.
That game with or without RT eats even beefy CPUs for breakfast even at PS5 settings whereas the console chugs along just fine.
How are you defining chugs along fine? As above, until we see matched settings (or as close to matched as possible) in the same areas I don't see how you're reaching this conclusion.