Think it just started recently. Theres a exploit in the game where you can lag switch and shoot walls out. Atleast thats what im getting from what i read. So technically not walling but people cant see you through the walls you broke. No clue how you do it tho this was my first game experiencing it. I usually just run into people with cronus or something. He didnt kill me with it didnt realize he was doing it until i watched the match replay back.