The changeling's Shapechanger trait says (E:RftLW, p. 18; WGtE, p. 61):
As an action, you can change your appearance and your voice. You determine the specifics of the changes, including your coloration, hair length, sex, height and weight. You can make yourself appear as a member of another race, though none of your game statistics change. You can’t duplicate the appearance of a creature you’ve never seen, and you must adopt a form that has the same basic arrangement of limbs that you have. Your clothing and equipment aren’t changed by this trait.
So basically, as long as the person you are changing into is/was a real person, you are always passing yourself off as a different person.
The second benefit of the Actor feat says (PHB, p. 165):
- You have advantage on Charisma (Deception) and Charisma (Performance) checks when trying to pass yourself off as a different person.
The way I read it, a changeling would always have advantage on Deception and Performance checks, because they are always trying to pass themselves as a different person. Is my interpretation correct? Or is the meaning of the Actor feat that they only have advantage when they are trying to prove that they are a different person, not in other situations?
I'm really curious whether this is kinda broken, because a bard or rogue with Expertise and advantage on all Deception checks could be a crazy good liar.