Is it a mod compatibility issue?

Yes

If it's a mod compatibility issue, please provide the link(s) to the incompatible mod(s)

https://www.curseforge.com/minecraft/mc-mods/moonrise

Minecraft version

1.21

Describe the issue

The game crash at startup when both moonrise and immersive portals are installed
latest.log

As this happens on Fabric too, I'll transfer this to upstream