Your buns turned out to be hard why is that?

Hard buns can result from several factors, including over-kneading the dough, which can lead to excessive gluten development, making the texture tough. Additionally, insufficient hydration or baking at too high a temperature can cause the crust to harden too quickly. Finally, under-proofing the dough may prevent it from rising properly, resulting in dense, hard buns. Adjusting these variables can help achieve a softer texture.