why is the momentum like that? the momentum seems to be kept unless you release all keys, which means diagonal movement basically forces you to drift
the gameplay would feel more standard if the fih always kept the same slippery momentum and were forced to manually stop it every time rather than secretly having a "stopper" mechanic only when you release all keys, though i guess it can be worked with. maybe instead of changing the mechanics, just having a large open area without bumps where you can swim around and experience this drift would be enough to at least inform players about it? idk
also i personally would recommend a circle instead of square hitbox for the spikes and definitely for the fih so we dont get caught on the corners a lot but that's just because i have skill issue and need to get better at game instead
still, fih is fih
P.S. you can swim backwards hehe