I've noticed that the GUI looks much sharper on PS5 as well. That's just how it is. For games though you really have to take it case by case. XSX is marginally more powerful than the PS5 but it ultimately comes down to what the devs actually do the work. And I don't mean that it should be better on XSX but it should be equivalent. It may be an HDMI cable as others have said or it could just be a game where the devs didn't optimize the Xbox version like they did the PS version. Callisto Protocol for example.

Also, check if maybe Xbox version is in performance and the PS5 version is in quality mode or something like that.