It's common that even though you've moved out, are an adult and responsible, you almost become like a child again when you return to your childhood home.
This role change also applies to parents. They may expect the same patterns as when you lived at home. Conflicts and disagreements in the family don't always disappear just because you move out, and they can return in a slightly more intense form during the Christmas holidays.
Take a break during Christmas and set boundaries. It's perfectly okay if things don't live up to expectations. Maybe you can stay with friends or other relatives for a few days? It's okay to take care of yourself, despite what mom and dad want.