You must use a special Apple-provided cloth to wipe the Apple Pro Display XDR

Apple's new Pro Display XDR comes with an optional nano-texture glass that bumps up the price of the monitor by an extra $1,200 from an already jaw-dropping price of $6,299. The panel is etched at the nanometer level that helps cut down glare and reflectivity. But as we just learned, it needs to be cleaned with a special cloth. A dry polishing cloth provided by Apple should be the only thing you use to wipe the glass. Water or liquids shouldn't be used. 

According to an Apple support document, you mustn't use any other cloth for it. And if you lose it, you need to contact Apple Support for a replacement. It isn't clear how much the fabric will cost. 

Apple also has specific instructions on how to clean the cloth. It needs to be cleaned with dish soap and water, rinsed thoroughly, and then be air-dried for at least 24 hours.

As for the standard Apple Pro Display XDR, a standard microfiber cloth and a bit of water will work. The casing itself can be cleaned with a soft, slightly damp, lint-free cloth.

Source: MacRumors