Today while playing on the TF2 VS SAXTON HALE #1 server most players exploited such a bug. The time of the screenshots and demo was about 20:45.
Mreow SkySpy, as far as I know, Echo is already on it, maybe hes even contacted Snelvuur about it, thanks for the report.
Mostly people who either want a challenge against an overpowered boss (compared to the vanilla classes) or people who want something different than vanilla TF2.
The issue has been solved a few hours ago, next time when the rankings update and should those scores apply to them the abusers will have their stats reset. Though if the stats do update constantly then it seems those damage points didnt count to them cause we'd have every single one of them in the top10 already. Also... lawl that pyro is funny on the bottom image.