A Piglin typically zombifies in the overworld, defined by a default NBT tag with a value of 0, IsImmuneToZombification. If their data is modified to be unable to zombify, then it should pass NBT tags down to babies, at least reasonably. So...

1. Steps to Reproduce:
   To summon a piglin or hoglin that can't zombify:

/summon piglin ~ ~ ~ {IsImmuneToZombification:1}

/summon hoglin ~ ~ ~ {IsImmuneToZombification:1}

Ideally, this might be done using spawn eggs, so a command respective to each spawn egg for spawning piglins and hoglins that don't zombify:

/give @p piglin_spawn_egg[entity_data={IsImmuneToZombification:1}]

/give @p hoglin_spawn_egg[entity_data={IsImmuneToZombification:1}]

1. Use the spawn eggs or commands to spawn a piglin or hoglin that doesn't zombify.
2. Use one of the two spawn eggs (ideally) to spawn a baby from a parent piglin or hoglin. It should zombify.

Expected Result: The babies from the parent piglins and hoglins don't zombify.

Actual Result: The babies from the parent piglins and hoglins zombify.

The file with a recording of this bug is too big for the bug report, thus a Google Drive Link provided:

https://drive.google.com/file/d/1aXxmYbN8hXLK1XCRNWfvh-rDl56GbaRv/view?usp=sharing{}