Description:
A rare bug has appeared in the modpack Rebirth of the Night which includes the Stygian End mod. When creating a new multiplayer world via server pack in the latest Beta (2) 3.0 version of RoTN, Stygian End biomes appear to spawn in the Overworld dimension at a rate that is similar to how often they spawned in the End dimension.

This issue is only replicable via the server pack version. Singleplayer has no similar issue.

Screenshot:

Further link to the issue:
#558

Link to RoTN:
RoTN Curseforge