Neoforge Modding Question

I'm attempting to make a mod for the world I'm in, I want to make a Neoforge 1.21.1 mod. The options for neoforge are 1.21.1 or 1.21.8. Now 1.21.8 has full support, but 1.21.1 cannot mod blocks. Is there a reason for this or a way around it? I did try but I just get purple textures.