Projectiles' velocity is wrong when jumping

When jumping and throwing projectiles (Bow/Arrow, Snowballs, Ender pearls, etc.) the y velocity seems to be wrong. It feels like the velocity of the player and the projectile is multiplicated instead of added.

The bug seems to be on the server considering it doesn't do it on a single player map.

In the screenshots I'm currently jumping and the snowballs are getting thrown quite a lot higher than they should.
Screenshot #2: I'm throwing almost horizontal and the snowballs are getting thrown off screen in the air
Screenshot #3: Bug reproduced with the following command on a repeating commandblock:

/execute @e[type=Snowball] ~ ~ ~ summon ArmorStand ~ ~ ~ {NoGravity:1,Tags:[test],Marker:1,Small:1}

Steps to reproduce:
1. Connect to a hosted server
2. Get some snowballs
3. Hold space
4. Throw the snowballs in the air at about 15° up.