Emerald ore and infested blocks do not generate in Snowy Mountain biomes in 1.17.1.
I have attached a map from seed 231065416999680 showing emerald ore distribution per chunk. The area labeled "Snowy Mountains" does not contain any emerald ore. One area of regular/wooded mountains was generated in 1.17.0 so has a higher emerald ore distribution than the rest of the regular/wooded mountains. The snowy mountains were generated in 1.17.1
The map for infested blocks is roughly the same but with different distribution densities. None in the snowy mountain biome.
I could confirm in 1.17.1 though this was fixed in 21w40a