You didn’t specify what the balloon is filled with. If it is less dense than air: to the left as the air is pushed to the right pushing the less dense balloon to the left. If the balloon is filled with something denser than air: to the right as it pushes air out of its way.
thunderstorm99 t1_j6c72ta wrote
Reply to comment by Youdontknowmypickles in TIL that air is a fluid by andreasdagen
You didn’t specify what the balloon is filled with. If it is less dense than air: to the left as the air is pushed to the right pushing the less dense balloon to the left. If the balloon is filled with something denser than air: to the right as it pushes air out of its way.