Minecraft texture pack rendering bug- swamp grass generates with snow grass on sides

So I was working on a texture pack and when I took it out for testing I noticed in swamp biomes, the grass generates with the snow grass texture on the sides. I have only changed the block textures, not the actual code so I am very confused. Normal texture free minecraft is working fine. This is very irritating and I need to resolve it as it ruin the texture pack to be honest and I was hoping to get it on the marketplace. I can't sell a pack that generates buggy swamps. I got the pack download of of the minecraft website so it's all official and untouched.