The video is in Portuguese, but basically you can only do this as a defender.
You need to get a defender that has a shield and go outside. Near the ladder that takes you to the basement you have a powerbox, you need to place the deployable shield between the wall and the powerbox, then, you need to get between the shield and the wall, a friend of yours needs to vault the shield, pushing you to the inside of the wall. When we discovered this we found two outcomes, one where we get pushed inside the powerbox and one where we got pushed inside the kitchen wall. You cannot shoot through the powerbox, but you can throw explosives and other stuff. I find this glitch useless, unless you’re trolling, as it needs to players to work and it doesn get you any advantage and can end with both of you failing and getting killed