When a player has very large levitation values, it causes thrown entities(arrows, snowballs, etc.) from that player to also have levitation and fly higher than they normaly would(for very large values, even flying strait up).
To reproduce:position youself underneath a block so you don't fly up, type /effect @p minecraft:levetation 30 255, then throw a snowball. it will fly strait up.
Related issues
Comments


Also duplicates MC-99406. (The thrown projectile is taking on your own velocity added to the velocity that it would ordinarily have had with 1.8's algorithm.)
Effects with amplefiers over 4 are not supported