Probably for storing the time & temperature settings for things you cook often.
Like for when you get the timing dialed in and figured out just right for a specific brand and flavor of microwave popcorn.
It's Chaos Defrosting named after Chaos where no one knows what's going on. Microwave oven manufacturers found that defrosting stuff by giving them random bursts of microwaves as opposed to a steady stream of energy defrosted frozen stuff quicker and better. So that's what it means if you've got a Chaos button on your microwave.
Maybe you'll get super powers if you put popcorn in it and press that button
Like for when you get the timing dialed in and figured out just right for a specific brand and flavor of microwave popcorn.