Vollying with grip slightly higher?

I may be crazy but I noticed that when sinner volleys, he seems to grip the racket a little bit higher. What I mean by that is usually the butt cap of the racket rests in his palm when he serves or hits ground strokes but when he volleys you can see he slightly shifts the grip up so that the end of the racket peeks out a bit. Hard to tell if he grips continental too but I thought it was interesting as my coach and YouTube tutorials never say to grip the racket a little higher on volley. See this vid for what I’m talking about: https://youtube.com/shorts/vg2Xom7mHKI