it has nothing to do with the brand, and everything to do with physics. it's static electricity generated from the paper-backed belts rubbing at high speed against the metal frame of the sander (think of dragging your feet in socks across carpet then touching your little brother/sister's ear
). ANY belt sander will do this if it is not equipped with some type of grounding mechanism that runs from the equipment to the user. In the industry it's called an ESD (electro static discharge) mechanism. It provides a grounding path between the source of the static charge (the equipment) and the source of the ground (the user)
https://www.amazon.com/StarTech-com-.../dp/B0002QKMEG