speed of the jump when you move up is constant where it shoud be quickest at the start and the slowest whene the player is at their peak. but ths varies for diffrent type of feeling of the platformer, so you might want to experiment with that. and the movmnet shoud be normilized (the lenght of player direction vector shoud be capped at leght of 1 so (Vector2(1,1)->Vector(0.707,0.707) and so on))