What caused the metal flake to separate like this?

You can see it on the cowl area as well as the doors. This started with my first light coats and while it’s far less now I’d like to know why this happened-it’s only in a few places and isn’t super noticeable from a distance. Also, would hitting it with another coat of paint help or not?

Paint is MCW enamel thinned with Mr. Hobby leveling thinner, and airbrushed over Tamiya primer. I had this happen once with a spray can as well-I just don’t want it to keep happening! Thanks!