This release fixes an issue in new world creation where water creatures were not spawning naturally because the FLAT type of world height of the world became -63, i.e., one block above -64. Unfortunately, this fix doesn't change existing worlds. It can only affect new worlds.
Use are your own risk! Take a backup copy of your world beforehand
You need to edit or replace the level.dat file in the bskyblock_world folder. The simple approach is to copy a level.dat file from a generic world and paste over it, e.g. the world folder's copy. Then restart the server, and it should work. Alternatively, if you have a NBT editor, then you can change the level.dat file of the world NBT tags to look like this:
!image
✔️ BentoBox API 2.7.1 or later only ✔️ Minecraft 1.21.3+ only ✔️ Java 21
Full Changelog: https://github.com/BentoBoxWorld/AcidIsland/compare/1.20.0...1.20.1

Classic SkyBlock survival for multiplayer servers. Start on a floating island with limited resources and build your way up. Powered by BentoBox.