Like above. Is this possible to recreate only the below y=0 chunks parts? Like, is there some mod, application or whatever?
If no, do anyone knows how are the biomes set in there? If I will. for example, cut everything below y=0 from 1.19 new world, and paste it in my old world - will it still be considered deep dark biome? Thanks for any hints, you will really save me a lot of work there