As the title says, CM's arm clips through her bracers as her arms move/rotate out and away from her default stance. It mainly occurs at the middle of the forearms, and is evident in-game, the loadout screen, and in Source Film Maker. Here are some images that show the clipping in-game and in the loadout screen:

I haven't tested it with her arcana or other bracers, so it's not clear whether the issue is in the base model or the basic bracer.