The effect is from post process package from unity. I use both Bloom and Chromatic Aberration and raised the intensity value of these two for a second whenever the ball get hit. There also a little bit of additional value tweaking but you can try explore that and see what it do. Additionally, I also adjust the bloom color too depending on if the ball is red or green. There also a screen shake which I create by moving the camera's position randomly. That would be most of the juice in the game, hope that help!