Minecart floats when going down a spiral

When pushing a minecart down this spiral, it not only goes down slow but visually floats, however the hitbox is still on the rail.

Steps to reproduce:

1. Create/open a world with the Minecart Improvements experiment enabled
2. Build a spiral:
   
3. Place down a minecart at the top and push it down the spiral

Observed result:
The minecart visually floats when going down the spiral.

Expected result:
The minecart does not float when going down the spiral, like its hitbox would suggest.