A very nice game! The rewind effect worked excellently (maybe a bit fast). Unbelievable that you had a personal and a team project. Can't imagine being able to do that. The small spatial distortions that happened near the end was charming. I had hoped for some more, and the last level seemed to be a bit of a repeat of an earlier level.
The hitbox for grabbing the key was a bit weird. I kept falling through the key, and was only able to pick it up when falling alongside it. And it seems like you needed to press the button as you were in the hitbox, which is very tight. Maybe making it only require the button being held to pick it up, and then press it again to drop it.
Also, with Unity WebGL, it's better to turn off itch's implementation of full screen, since they don't work well together.