That's bad, please don't eat it. Because cauliflower needs to be sprayed with pesticides many times during the whole growth process, otherwise it will grow a lot of bugs. So it is safer to soak for more than 20 minutes after washing, and then fry it with boiling water. Even if it is scalded with boiling water, it will not turn black, but it will still turn white. If washed with hot water, it will turn black. If it is not normal, please don't eat it.