Serious answer:
Apple's polishing cloth is the only cleaning solution that is officially certified for Apple displays that have the anti-reflective nano-texture glass option, which is available for the Pro Display XDR and high-end iMacs. Apple has now made that same cloth available for all of its users. Considering the price of the nano-texture glass, there is no way I would risk using anything else. For other Apple devices, it is simply guaranteed to be a high quality cleaning tool, but not required.
I have a 21.5-inch LG UltraFine 4K and use standard microfiber cleaning cloths, those that you would get from an optometrist, and they work fine without damaging the screen coating. If I were to purchase a new Apple display (or Apple recommended monitor, like the LGs) then I'd get the Apple cleaning cloth, just for peace of mind. Long ago, I had an IBM CRT monitor with a glossy glass screen, which I accidentally damaged because a small piece of debris was caught between the cloth and the screen while I cleaned it. The monitor ended up with permanent scratch marks everywhere I had used the cloth. I now make extra certain that the cleaning cloths I use are new or fully washed before using them to clean a screen.
Even if it's overpriced, I would still spend extra for the Apple cleaning cloth if I purchased a new Apple display or a monitor that Apple recommends. I'm sure I'm not the only one that has this notion, hence the sellout of the cloth.