The Lady Doth Protest Too Much, Methinks
Gertrude herself is the one who says this key line. She’s speaking about an actor who is playing a Queen in a play they’re all watching. It’s a play within a play, and Hamlet has staged it to try to draw out the supposed guilt of his mother and uncle. Thus he’s made the Queen character especially dramatic, to the point that Gertrude herself is basically like, this lady needs to take it down a notch. It’s very interesting that she speaks the line to a version of herself, rather than Hamlet to her.