Monitor inputlag?

So I wanted to ask something before I make a mistake. So I play Fortnite on ps4 but with mouse and keyboard but in the game the whole thing feels different as if I have input lag I have a monitor that I think has no input lag and I wanted to ask is it on the PlayStation or is it the normal way if not, is it on the monitor maybe? But on controller it feels normal somehow

Since the mouse translates the movements much more directly, but the frame rate remains the same, it clearly feels less fluid with the mouse.