Looks suspiciously like acrylic vs celluose vs 2k reaction. Meaning whatever was below is reacting with stuff on the top. Or possibly primer was still wet when top coat went on.
Is that not something that a heavy flat and polish and a couple more coats would remedy?
I wouldn't polish it, but he
may get away with flatting the whole thing back, proper wipe down and repaint, but I would be inclined to strip it right back as the only thing worse than doing a job twice, is doing it three times.