I’m pretty careful not to make comments regarding authenticity. I’ve had someone claim one of my caribou FBFs was fake simply out of ignorance. It didn’t fit his limited knowledge of Balenciaga but he made it sound convincing enough that some people might believe him. I know we may be right most of the time but it’s not a risk I like to take.Something along the lines of "so for clarification: is the bag for sale the gray or the green fake? Thanks!"
I did see that you can contact them so that might be the best thing to do. But it’s a PITA compared to hitting a report button!