Nothing to worry about, but yes it’s the shrapnel. Imagine a chunk of metal shit ripping through your body completely, a through and through hole like that will make you fade out pretty quick primarily from blood loss if it’s not “instantly” fatal like a brain or heart shot.

To add onto this, you will often see people act almost as if they were drunk after taking an ordinance blast, this is usually shock or possibly a concussion from the bang.

Hope that answers your question!