this occured on a minecraft server that was upgraded from 1.17 to 1.18 hosted by hypixel smp
https://www.youtube.com/watch?v=z_IsAgc-KWU&ab_channel=Spyder981
no plugins, no worldedit, only the default vanilla one
The biome in the end changed to planes in newly generated end-chunks
Mobs as well as bats are able to spawn there (look at the video).
Thank you for your report!
However, this issue is Invalid.
Your game, launcher or server is modified.
If you can reproduce the issue in a vanilla environment, please recreate the issue.
Any non-standard client/server/launcher build needs to be taken up with the appropriate team, not Mojang.
Any plugin issues need to be addressed to the creator of the plugin or resource pack.
If you have problems on large servers, such as The Hive and Hypixel, please contact them first as they run modified server software.
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