What is that white stuff on my cactus?

Product Description

Cactus (rotting?!)

identification - What is this white growth on my cactus? - Gardening & Landscaping Stack Exchange

Fungal / Mold Growth on Prickly Pear Cactus - Opuntia Mill. fungal infections, white fuzz, mealybugs

Caterpillar Cactus Plant Care: Water, Light, Nutrients

Cactus, Description, Distribution, Family, & Facts

Succulent Parasites: My Experiences

How to Get Rid of Mealybugs on Your Cactus (and prevent them from coming back) - Potted Pixie

What are the white spots on my cactus? : r/plantclinic

Beware of scale insects on cacti