My 8-year-old son asked this question and i couldn’t give him a definite answer. So he’s wondering if it would do the same thing as a balloon pushed underwater in the bathtub (which kind of makes sense to me, due to the density differences, not just gravity alone).
But I told him I’d ask those more knowledgeable than me.
Push a balloon under water and ignore what’s happening in the vertical direction, just pay attention to how the two interact in the perpendicular to gravity plane.
The other answer is the balloon would pop and the water would evaporate but I’m assuming you mean just a 0 gravity environment and not a vacuum