I think they were surprised at how unhinged he got, and looked impotent with rage.
He's usually surrounded by sycophants that he can bully around and they get linched by his mob if they don't fall in line. Or he just gets up and leaves any interview that challenges his bullshit, and can leave with the last word. His childish tantrums can get reduced to soundbites that make him look like the winner to his followers who are also petty adult children.
But here, Harris was in frame laughing at his meltdowns and clearly easily pushing his buttons where it hurt, and he could do nothing but stomp over the so called moderation to steal airtime, just to look like a petulant child who needed a nap.
You could tell she had those zingers locked and loaded and was just waiting for the right time to drop each of them.
You could also see her when she decided to chamber the round. Where her stern disapproval face had brief flickers of delight as she decided she was going to use one when she had her next chance to speak.