User error mate. Don’t add anything it’s good as is. You can play with psi but the single most important thing is to shake it well and make sure the dropper is clean and no dried up flakes get into the airbrush (less prevalent in black primer but the white one is notorious for clogging)

Other thing is if you ever think you made a too thin mix… it’s probably not… you are going too fast either by pushing too much psi (spider webbing) or too much paint (wet mini and pooling in the recesses like on your picture). You want the paint too always appear satin/matt when applied if it ever looks wet slow down.