PUBG being intertwined with cheating is no news but creative new ways of cheating definitely are. Cheaters have employed wall hacks, no recoil, aim bots and teleportation in the past but the latest exploit sends them sniping below the map.
Once the cheater is under the map they simply wait it out until the rest of the players kill each other. When it comes down to two players standing, the cheater simply snipes the last player from under the map. This exploit allowed them to remain undetected because they wouldn't kill a pile of players who might get enraged and report them. If they kill only one person they can remain undetected for a while because it would take time to generate enough reports to actually get banned.
Reddit user wanfreestyler accidentally found out about an exploiter after watching a victory replay. The cheater waited it out until only they and wanfreestyler were left standing. The circle eventually closed completely due to the game's length which caused the cheater to lose health and die because apparently they didn't understand they were losing health. You can see the entire "fight" on this link.
Other redditors quickly searched for the cheater's profile on op.gg and discovered that the person in question was #14 on South-East Asia's leaderboards with an 80 per cent win rate with a fairly low KDA ratio for a cheater. This proved the point that the person wasn't aggressively killing other players but was rather waiting it out in order to avoid reports and automated cheat detection.
Considering this person didn't know about the circle's detrimental effects to their well being, it is highly unlikely they had the skill or ballistic knowledge to score a kill at 873 meters but they did. This implies that the user also used an aim bot, but the distance is likely that high because konijiwa666 was so far down below their victims.
Either way, this user is apparently still not banned and it remains to be seen if PUBG Corp will consider this topic's video a piece of admissible evidence.