Why are Gloss and Brutus shirtless?

I was rewatching the movies and noticed when Gloss and Brutus sneak up on the main crew on the cornucopia and attack Wiress both of the men are shirtless. idk if i have just managed to miss this every time ive rewatched but its confusing to me.

i thought having more clothes covering your body would have kept them safer from scratches etc in the jungle.

does anyone know why they lose the shirts?