There is an invisible barrier at height limit (Y=256 and Y=320)

When you're flying up above the height limit, and fall back, you will hit an invisible barrier that prevents you from falling further. This isn't supposed to happen.

Step to Reproduce
1. Do /tp ~ 260 ~ in non experimental world, or /tp ~ 330 ~ in Caves & Cliffs experimental world
2. Fall down.

Expected Result
You fall all the way to the ground.

Observed Result
Your fall stops at the height limit, for some reason...