Hello, I liked your game, but I will give you some ideas you might be able to use for your game.
I got stuck on a level (unable to move) and was unable to exit or restart the game without refreshing the page. It might be a good idea to have a pause menu where the player can restart the level without having to die to avoid situations like this.
The spikes feel as if the hitboxes are too big. I don't know if there are, but I felt like I could pass over a spike or that I had enough room, but I did not. Geometry Dash has a good implementation of spike hitboxes that feel right (at least to me), and it might be worth it to check it out. Actual Size of Hitboxes (Credit: @absolllute) : r/geometrydash (reddit.com)
A good way to do music in Unity so it does not fade in or glitch weirdly is to have a script that makes the game object that controls the music a DontDestroyOnLoad() game object. This thread could help you with the ways to implement this. c# - Duplicates because of DontDestroyOnLoad() - Stack Overflow
I tried clicking a button once, and it activated multiple times. I recommend adding a small timer before it can be reactivated or another idea to limit this.
I wish you luck on whatever you do next and have a nice day.