[Bug]: mobs spawn in accordance to vanilla biome generation, disregarding actual biome generation

[Jack-McKalling]

General Info

• I can reproduce this issue consistently in single-player
• I can reproduce this issue consistently in multi-player
• I have searched for this issue previously and it was either (1) not previously reported, or (2) previously fixed and I am having the same problem.
• I am crashing and can provide my crash report(s)
• I am using the latest version of the modpack

Modpack version

1.0.5

Java version

1.16.5

Modpack Launcher Used

ATLauncher

Memory Allocated

2048MB (initial); 4096MB (max)

Minecraft World Environment

Single Player

Misc Client Info

• Optifine Installed
• Shaders Installed

Server Java Version

No response

Server Operating System

No response

Misc Server Info

• Sponge or Non-Vanilla Forge Server

Issue Description

Mobs spawn according to the vanilla biomes that would generate if you recreate the seed in the vanilla game.

My island reports (below JourneyMap) that I'm around a mountain and birch forest hills area, however a polar bear spawned on my grass blocks and no bats spawn in my dark room. Because I tested the same seed in vanilla, and the area is actually in a cold ocean biome.

Either journeymap is not reporting the biomes correctly, or the skyblock topography is doing something wrong with biomes. Because mob spawning is incorrectly tied to the vanilla biome seed rather than the modded biome seed. This cannot be intended.

Additional Information

My world seed is -6411042652787668816, coords -50/1/6