Splash potions thrown underwater straight up or down break instantly

The bug

When completely underwater and with space around you, throwing a splash potion straight up or down will cause the potion to break immediately.

How to reproduce

1. /fill ~ ~ ~ ~10 ~50 ~10 water
2. Go in the middle of the water
3. Grab a splash potion
4. Throw it straight up or straight down
→ It breaks right away

Expected behavior

When thrown straight up, potion should move upward, giving you time to move out of the way if you wish. When thrown straight down, the potion should fall, outspeeding you

Video