Besides pbr textures, this package also includes a diffuse map and one textured material for performance. Performance dif means it only uses one texture. normal map doesn't need metalness or specular map (etc). Because they are all in diffuse. However, it is not affected by the light in the scene. So if you need low specs that it can be used in your game more efficiently. You can either use pbr textures or use single texture.
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