Zara Women's Large Short Sleeve Black Shirt Dress Partial Button Front READ

It is new and still has the loop around the inside tag BUT it has a mark on the back. Please see all photos. I am not sure if it can come out or what it is. Zara women's Large short sleeve partial button front dress is collared and is made of 100% polyester. It measures 21 inches from underarm to underarm laying flat and 35 inches from shoulder seam to hem.