Calling it a fatal wound doesn't seem wrong.
But for Yun You, things are a bit different.
Because as long as Yun You doesn't lose consciousness suddenly, or her brain isn't damaged, she can repair those fatal wounds through eating.
As for why her hands can still move after losing her head... well, you'd have to ask Master Zero.
The Red Scale Giant Claw, although Yun You has complete control, if she agrees, Master Zero can also take over for a short time.
And before setting off, Yun You had already discussed with Master Zero that once her brain was struck and she lost control of her body, Master Zero would help her put her head back on.
Thus, this resulted in her bold actions.
Though the little girl is brave, she's never been reckless.
She will try to calculate all possibilities to overcome obstacles.
