No. I can say this with confidence because I am an expert on war crimes - I have consumed two, maybe even three distinct pieces of media where war crimes have been mentioned. At one point I even glanced at the Wikipedia article on war crimes. You can count on me.

For real though I think throwing a frag grenade into an enemy army’s bunker can’t possibly be a war crime. The deception with the tin cans isn’t relevant.

It’s never a war crime the first time.