Hey! I just played your game, it looks nice and I liked the music while playing, it feels that you tried to sync the music with the way that the balls spawn and that's really cool. Also I have some tips but I am not an expert myself, so yeah.
First, I was hit by the balls when they were spawning, I think that if you could make the collision a second after the balls spawn it would be good.
Lastly, I think it could help if you showed the lives that we have not as a number but as a picture or something else, maybe just make the font bigger, it would be easier to read or notice while avoiding the balls