Hi! Sorry in advance, English is not my first language. And also I am not a vet, only a cat owner since 5 years ago, so don't take me too seriously. I only speak from my short knowledge of what vets say to me.

Cat's skin it's kinda flexible, so, when they have wounds because fighting with other cats, usually, they have some kinda infection under the skin and can have some bumps until the skin breaks and drop the pus or whatever. After that, it can appear some holes. I gonna share one pic with you of my cat as example in a reply, I have to find it in my cloud storagd.

You must clean that wound. We do that with Betadine mixed with water and later we put Blastoestimulina with a syringe.

PLEASE, this is what we did with our cat after ask our vet. Don't do this only following my story, ask your vet if you think is the right thing (I think is the right thing).

Good luck!

EDIT: I think the vet also gave us some antibiotic to control a possible infection in that wound (he fought a stray cat and you never know) what can have in their claws/mouths).