In full screen it is hard locked to 72 FPS which is half my refresh rate, I presume the game has a forced half v-sync mode? If I put it into windowed mode I can get the full 144 FPS, however because it's not a resizeable window, I need to put at 1440P to fit on the 4K display, and 1440P window is too small, so hence, full screen it is.
Why this limitation? I have tried to force v sync off in GPU and see if that helps.
But just adding a v-sync option to the game itself is the answer.

That and the control issues I was having, I don't know, maybe I should get this on PS5 instead and return the Steam one.

Does anyone know if the xbox store one is better? Sometimes the issues are different between versions. I don't pay for game pass ultimate anymore so no longer have access to it hence why I bought the game.