The generation of nether biomes seems nonexistent. there are no Nylium or trees in either the warped forest or the crimson forest and there is no soul sand in soul sand valley biomes.

Steps to Reproduce:

1. make new world in 21w38a snapshot

2. go into the nether and use the command /locatebiome and locate either crimson forest, warped forest, or soul sand valley

3. observe that the issues listed above are true and stuff doesn't generate

Observed Results:

no Nylium or trees in either the warped forest or the crimson forest. no soul sand in soul sand valley biomes.

Expected Results:

there should be red nylium and crimson trees in the crimson forrest. blue Nylium and blue trees in the warped forrest. souls sand and soul soil in the soul sand valley biomes