Hard to tell from the photo, but to me it looks like its just scratched in (through?) the resin finish layer. From what I can see in the photo, I’d use it without worry. My experience with these bottles comes from the paintball world where I was not only a player for 25 years, but a touring gun tech for a manufacture and some pro division teams. The abuse that tournament paintball players put their tanks (and expensive markers) through would shock most people not accustomed to it, and I’ve seen tanks with similar scratches all over them.