There are black paints i think inside wheere it connects the earcups and headband , seems everytime the earcups flexes , it scrapes the paint a little bit
Seems it occurs in the around the part where the headband connects . There is like a black paint which surronds the ball or part where the headband connects to the earcups , the right pair seems ok but the left pair seems to peel of maybe because of the flexing of the earcups? Am not sure