Decided to test out some datapacks and confirmed that one I was using that relied on "origins:prevent_entity_render" only fully worked on the fabric version.
If you want to test it yourself here's the origin: somniabh.zip
Essentially what's supposed to happen is if entities are effected by glowing then they will render but otherwise they will not render. The forge version made them always not render.
Here's the exact power that doesn't work:
threat.txt
(I switched it to a .txt file).

After more testing it seems to be a rendering issue with... Pehkui? All I know is when pehkui is removed everything works fine.
Edit: Nope nvm it isn't.