That is actually a defect of Unity's box colliders. I spent a little bit of time trying to rectify it, but ran out of time before I could completely smooth it out. Thanks for playing!
Viewing post in No Jumping. Take the Fall. jam comments
You may already have figured out what the issue was but since it's a gamejam and we're all trying hopefully helping and learning, you may want to check that the colliders are not overlapping, add a PhysicsMaterial2D with friction set to be a little lower, and possibly freeze Z rotation on your character to fix the collider issue (though if it doesn't break gameplay elsewhere, I'd keep it in, it adds flavor).