When you are riding an entity through portals, you and the entity may teleport to the wrong place

The bug

When you are riding an entity and teleporting through portals, you and the entity may teleport to wrong place and fall/suffocate/fall into the void.

Steps to reproduce:

1.Create a superflat world (This bug can happen in default world type, but in superflat worlds it seems always occurs)

2./gamerule entitiesWithPassengersCanUsePortals true

3.Go into the nether.

4.Summon and tame a horse and ride it.

5.Go back from the nether to overworld with it through the portal.

Observed result:

You are teleported into mid-air and fall, then the horse died(in survival you will also die)

Expected result:

You are teleported normally to the overworld portal.

Notes:

This affects both nether portals and end portals.