Describe the bug

Even when a game stage is not reached, plague zombies, mushrooms, and burning zombies and skeletons can spawn ON SPIDERS. this only happens on spiders

To Reproduce
Steps to reproduce the behavior:

open up a world, and watch mobs spawn during the night, make sure you haven't unlocked any game stages.

Expected behavior

later game mobs don't spawn on spiders in the earlier game stages.

Screenshots

don't have any but know others who experienced this

Info (please complete the following information):

• Modpack Version: 3.0.0
• Server or Singleplayer: Singleplayer
• Version the world was created on: beta 4

Additional context

idk how to fix but it definitely works differently from normal mobs, I suspect for the mod dev to have added the possibility of the mob riding on a spider there should be a way to refer to it specifily in the source code, but idk cause they are 2 different entities, so maybe if you could make it so the mobs can't ride on spiders until the game stage requirements are met and they can spawn. that how I would do it.

This issue is not replicable on v.3.1.1a.