As far as I can tell, normal Piglins don’t spawn either outside of Bastions.
+ It seems Ghasts and Wither Skeletons don’t spawn at all
+ Skeletons and Endermen don’t spawn in the Nether (or End), only the Overworld
Seems intented by "As if that wasn’t enough, you can bury the firefly bush below other blocks to make them sparkle!" from the blog post.
Entityyy
As far as I can tell, normal Piglins don’t spawn either outside of Bastions.
+ It seems Ghasts and Wither Skeletons don’t spawn at all
+ Skeletons and Endermen don’t spawn in the Nether (or End), only the Overworld