I love 2D platformers, Celeste is one of my favorite games. You have some good challenging levels here and they would benefit immensely from revised controls, which have already been discussed. I noticed you said that a small wall jump should occur if the player only pressed Spacebar while against a wall, but for me it was the opposite; only hitting Spacebar gave me a big jump and attempting to hit A/D would kill/diminish the jump.
Functionality-wise, your usage of mode here reminds me of the pink/blue alternating rhythm blocks or the switching between ice vs lava sections in Celeste. What those have in common is that you can always see where the objects/platforms in the other “mode” will be, so it feels fair. I would argue that’s my biggest gripe here, especially in the level where there’s a horizontal moving block in dark and another horizontal moving block in light, but they get desynced from each other.
You’ve got good ideas here, like how it’s not just the environment but also the character’s movement ability that changes with the mode. Having revised controls and improved indicators would help it shine.