I believe it was sold into the US market originally. I bought it second hand in a secondary market that sources its used articles primarily from the USA and Canada.
It would actually be way to miss. If it hadn’t been marked with a sunglasses emblem, I would have easily thought it was just a gusset. It’s just one of the bottom front corners of the left side of the shirt, with a triangular gusset that is big enough to just hold 2/3 of a pair of glasses, mesh, in this particular case.
