When small animals, such as cats, go through a stronghold-portal to the end dimension, they get stuck in the obsidian platform and begin to suffocate. Sometimes they die before the game loads to a playable state.

Steps to reproduce:

1. Get a small animal
2. Push it or get it to go through the stronghold-portal
3. Go through the portal

Observed results:

The animal will begin to take damage while the game is loading. First noticed this behavior when transporting cats. Breaking an obsidian block may save them if it isn't too late.

Further testing revealed that chickens and frogs also take damage. (Wolves probably do too but I didn't test.)

Expected results:

The animal should land on the obsidian platform instead of in it.

Perhaps a fix is to spawn a block or two higher?