I happen to have both 2021 iPad Pro 12.9 and this new 14". I will say the ghosting you see people complain about is here in the XDR display of the new mbp - it is also present in the scrolling of the ipp 12.9 as well as the non miniLED model of the 11 IPP which I also have. but it's nothing as bad as they say this is purely subjective. In the IPP there are no windows to drag around so you don't notice 99% of the time except when you go looking for it during a scrolling of a webpage, etc. On the XDR of the MBP, you can move a window around and depending on wallpaper background you can see the pixels ghost. It reminds me of my old gateway VA display. But it's not even close to being THAT bad.
Overall I think the IPP 12.9 display is awesome but the XDR on the mbp is even better because when I play HDR content only the window portion is super bright - on the iPad everything just looks bright. You're not going to get gimped here on the display of the new mbp. well maybe the ghosting issue is annoying for some overall it is a fantastic display.