The ReGrowth 2 mod, as I understood it, made some changes, and mods that refer to one of its biomes (RG_TemperateGrassland, it would appear) are now throwing red errors. In this mod's case:

Could not resolve cross-reference: No RimWorld.BiomeDef named RG_TemperateGrassland found to give to RimWorld.AnimalBiomeRecord RimWorld.AnimalBiomeRecord

Possible Matches:
[Source: ESCP - Orsimer]
[File: C:\Games\Indiv\Rimworld\Mods\3244645352\1.6\Defs\ThingDefs_Races\Races_Echatere.xml]
[Source: ESCP - Orsimer]
[File: C:\Games\Indiv\Rimworld\Mods\3244645352\1.6\Defs\ThingDefs_Races\Races_Welwa.xml]

I can't update mods for 1.6 on steam currently due to steam changing how account sharing works. Waiting for it to be resolved. Non-retexture mods are updated on my github over at TheoPaysRespect or at the discord