Snipers cheating via drone sliding wall bug

TLDR: There is a bug that allows snipers to get through closed areas of the map and 'hide' in REDSEC game modes.

Was playing REDSEC Quads today with a group of 3 people who I could not hear at all. They were clearly in a party chat and I couldn't hear anything they were saying. 

I was trying my best to keep up with them and eventually they ended up in the middle of the map and suddenly disappeared into a Tank box without opening it. 

I asked in chat where they had gone and one of the guys communicated via voice in the squad channel and told me to do the following:

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I just wanted to report it because it's upsetting that anyone would be abusing this bug to get an upper hand over other people. 

I can provide a video if necessary.

[CM - Edited to remove exploit description]