Survivors Escaping w/o Hatch/Gate

Noticed something particularly unusual while playing earlier. Had survivors escape during the EGC without taking hatch or exit gates. I can only assume hacks as they were crossplay, but at the same time, I do have to wonder if there's more to it.
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otz did catch hackers escaping without hatch or gates, so most likely they were hacking if you swear they weren’t able to use either of those.
One survivor was dead, one escaped with a key via hatch which I promptly closed and triggered EGC, one survivor was slugged without unbreakable and one survivor was looping me at killer shack. Neither gate had been opened. Unless I'm missing something, it has to be hacks.
A second key, maybe?
Can you confirm without a doubt that they didn't find a key in a chest (since I assume they didn't have one on-hand; otherwise you would have already known)?