Steps to reproduce

MCPE-157930.mcworld can be used to execute these steps. It contains a repeating command block that places gold blocks next to the overworld-side nether portal to track the villager's elevation in the overworld.

1. Make a nether portal in the overworld at a negative Y coordinate.
2. Clear all blocks above in the area above the portal up to Y = 2
3. Go through the portal.
4. Relog in the nether or set your spawn point in the nether using a respawn anchor.
5. Spawn a mob next to the nether-side portal mob.
6. Push the mob into the portal.
7. Go through the portal yourself.

Expected result

The mob appears inside the overworld-side portal with you.

Observed result

The mob appears at the X, Z coordinates of the overworld portal, but at Y = 0, and falls to its death.