I always thought a “jet ski” was the kind you stand on, and they got banned, as opposed to a personal watercraft that you sit on. It seem like people are calling personal watercraft “jet skis”.
“Jet Ski is the brand name of a personal watercraft (PWC) manufactured by Kawasaki, a Japanese company. The term is often used generically to refer to any type of personal watercraft used mainly for recreation, and it is also used as a verb to describe the use of any type of PWC.”