Haha I love the switch in tone of the music. This game is super fun! And I love the simplicity of the idea of backwards snake. I found it super engaging on the third stage, having all these obstacles appearing while you're flying through. This was honestly one of my favorite games of the Jam in terms of fun!
My only bit of constructive criticism is that it starts far too slow. I like that you're introducing the concept, but the intro level takes a looong time even though you start off with only 3 length. I would suggest it more as a tutorial level with a separate option even or try to shorten it even further. I almost stopped playing the game before that first level completed and missed out on the real fun of the game!
Also maybe have the switch in tone be related to how fast you're moving. It doesn't fit super well on the first level for example, but it's a banger for the third haha.
Great job!