This has nothing to with negating gravity. It’s (maybe) a clever use of manipulating magnetic fields. If it’s negating gravity the so is a hot-air balloon.
A long time ago I read a book called “The Book of Truth”, by some psychic type guy.
He said UFO’s fly by negating gravity. When this is done, very little power is required for propulsion. And they had atmospheric resistant metals on the saucers.
But he said humans could not tolerate the high G accelerations, they would implode. The aliens have different anatomy.
FWIW.