The injury is almost gone if I see it right.
but it will happen again and again in young cats.
Usually, the wounds heal by themselves. If it is bad, it can be treated with an antibiotic ointment.
The licking of the wound delays the healing process. Sphinx cats are special and need a bit more care than other cats.
I can not see what kind of ointment she uses (regular or not).
I think Masha knows her stuff and she knows what she is doing.
I think she loves her cats more than her boys, so I'm not worried about them.