Summoned projectile makes an arc

So basically i am making a custom fireball entity and using the "Attempt to override the motion vector of" block to make it goes where the player head is pointing, but for some reason when the player's head is pointing up or down it makes an arc and goes exponentially up or down and i have no idea on how to fix that


Heres the procedure image:
https://imgur.com/a/VuVzXcH

Pls send help