u/Deep_Scene3151

Marie has been spending the entirety of Season 2 of Gen V training how to both expand her control and use her powers in a variety of different ways. Maybe she isn't 100% as powerful as she could be, but she definitely has a good grasp on her powers by now. She healed Polarity brain injury so well that it removed the side effects of using his powers, cured Cate from her injuries that were effecting her powers, she brought her sister back to life, and completely repaired the body of Goldokin's severely burnt body.

Even if Annie was unaware of all of this, Marie didn't have any comeback and just looked down right before the subject was changed. As if she herself is confirming that it's true but not wanting to say it out loud.