Our definition of ‘thin layer’ was qualified to say that this meant the markings on the fuselage were still visible.
This is the same at my current operator and every operator I've worked for; if you can still read the text, you're good. A low res image under overcast skies on top of a three-tone livery makes it look much worse than it likely is. I could get onboard with the idea that it might be a light coating of powdery snow, but I'll not judge the crew unfairly.