MC Version: 1.18.2
Forge Version: 40.0.12

It has been confirmed that if I load "Oh the Biomes You'll Go" mod(BYG, Available at: https://www.curseforge.com/minecraft/mc-mods/oh-the-biomes-youll-go) and its dependency Terrablender(Available at: https://www.curseforge.com/minecraft/mc-mods/terrablender) together with the mod "The Undergarden", BYG mod can work well but the mod world of Undergarden can be damaged and its biomes will not appear in the world.

I am using the latest version of those three mods and they are the only mods in my client.

This issue has also been reported to BYG Team(https://github.com/AOCAWOL/BYG/).

I think TerraBlender fixed this a few hours ago.