You know how could you fix that sfx, if the script that's the player controller, you could copy the part that checks if the player is on the ground, and make if statement that checks if the Jump button was pressed, when it's pressed the sfx plays, and the player is off the ground, the statement says that the player needs to be on the ground, so the Jump effect won't play. If this helped you, then I'm pleased to help. :)