Any non-mob based entity (arrows, snowballs, items, fireballs are mostly ok) that has their Motion updated by any source that isn't by use of the item itself causes the client to not properly update the entity position. The server updates the entity without issues but the client lags behind a good half second. This causes a teleporting motion.

Please fix

To Replicate:

use "summon minecraft:snowball ~1 ~ ~ {Motion:[1.0d,1.0d,0.0d]}" in a command block followed by "execute as @e[type=minecraft:snowball] run data modify entity @s Motion[1] set value 0.5d" even the slow speeds have issues.