I'm seconding (or perhaps thirding?) the error where the entire tropical jungle biome generated as exposed blackstone, basalt, and some exposed ores. Grass only generates in rare patches and trees are even rarer. This goes on for hundreds of blocks (like from -300 to -800).
I'm using 1.21.1 Neoforge, I have tectonic installed and I'm not using terrablender, and I'm using the latest versions of both Terralith and Tectonic