Hello! Thanks a lot for making this game! I just finished celeste, so I was in the mood for another platformer :p The idea of switching gravity is really nice, and gives an interesting dynamic to the usual platformer. Usually I dont really like this 'floatyness' in the jumps, but here I did not mind it so much, maybe because of the gravity swap.
One point of feedback I have is on the hitboxes of the spikes. I would always urge to the side of the player, i.e. better to make them too small than too big. Now it felt a bit frustrating sometimes, becuase it felt like I should not have died there. (I guess there are two ways to fix it: make the hitboxes smaller, or make the spikes larger.) The music and atmosphere are great as well! They fit the game perfectly ^_^
One other point of feedback is that it might be nice to communicate to the player a bit more what way gravity currently faces. Of course it is kind of obvious when you are standing on the ceiling, but still some particles the go the other way would be cool. Maybe even a game mechanic where you have blocks that fall in a certain direction, depending on the direction of your gravity.
Sorry for the long post, hopefully it is at least somewhat helpful! I actually also made a platformer for this gamejam that you could check out in return, if you are interested :p