i found multiple glitches and one suggestion.
1) i had quite a few times thet the ball stopped bouncing try when programming your dx and dy characteristics and an if or statement to keep them from going below say try 2.5. or on your dx because you want arch you may want to add a statment that makes it so that if it is at zero for x number of frames it will start to move at a 2.5.
2)i had my ball stuck in my paddle and couldnt get it oututill i learned to add spin to the ball just click on it. i could not recreate said glitch consistantly.
and last but not least try adding a mouse hid function along with another mouse follow with lets say a blue dot to match your paddle ends.
but i love the game so far keep up the good work!!