Just to be clear, it is not a "hot air" balloon.
(That's an important distinction.)
It is lifted by a "lighter-than-air" gas inside the bag.
An independent (not Disney) company operates these balloons.
Some of the gas accidentally escaped from the bag one of an excursion balloon in another part of the world a few of months ago causing the guests in the basket/cage to drop too fast (some were injured,) and the company has closed all of their ballon operations (for safety reliability checks) until further notice.