https://wccftech.com/2021-ipad-pro-vs-pro-display-xdr-local-dimming-zones/

When the Pro Display XDR was announced for $5,000, Apple aimed to tackle a market littered with overly priced reference monitors. Its specifications are legendary, with the monitor also having received an award for the best display. Unfortunately, it features just 576 local dimming zones. That number has been overtaken considerably by Apple’s latest 12.9-inch iPad Pro.

Thanks to the iPad Pro’s mini-LED technology, its local dimming zones go up to 2,500. This is possible thanks to the backlighting that allows over 10,000 LEDs to be placed. With LCD technology, it is not possible to add a large number of local dimming zones, which would explain why the Pro Display XDR features only 576 local dimming zones, despite its substantially larger display and expensive $5,000 asking price.