What an intriguing idea for a game! Rhythm Tetris? Amazing concept! Honestly, if you decide to keep going with this (which you absolutely should) please let me know. I'd love to see how you expand it. That said, I do have a few things to note.
For starters, I wasn't entirely sure what to do at the beginning. I saw my score going down, so I knew what I was doing was wrong, but I had no idea what that was. I later remembered the genre combination and decided to try moving to the beat, but it took an honestly embarrassing amount of time to figure that out. It's probably more on me for being a bit slow with this sort of thing, but maybe it would be a good idea to communicate the goal to the player more explicitly.
To that end, I think that where each beat starts and ends is a bit ambiguous. It just felt like sometimes I was hitting the button at the right time but still losing points. Again, it's probably on me, but I'll at least mention it just in case.
This next point is a bit nitpicky, but whenever a level is loaded, console windows appear all over the screen. Again, it's not game breaking, but it's definitely a tad jarring.
Finally, I would suggest giving the player some more feedback when they clear lines or move at the right time. It would just make the game more...satisfying, I think. Like maybe add some sound effects. Or some screen shake. Or only change the colors when the player does something on beat! That would feel really powerful and satisfying. Not to mention: it would reinforce the need to move on the beat.
Overall, you've got a super neat idea here! Please keep going with it (sorry to be forceful, no pressure :) )!
Oh, and really cool music! It got stuck in my head, but I'm not complaining.