Nether mobs are despawning once brought into the overworld despite being name tagged. Other mobs, friendly or hostile, found in the regular world have never despawned when named. However I built a home specifically for my pets from the nether, which has zero escape routes for them, and they keep despawning even after I name them.

What I expected to happen was...:
I expected them to never despawn because they are named.

What actually happened was...:
After a few days inside the game, they just vanish with no drops inside their house.

Steps to Reproduce:
1. Build a small house with no escape routes next to the nether portal on hardcore mode using only nether materials.
2. Transport a zombified piglin or strider into the house and name it.
3. Wait a few in game days and the mob might despawn.