Just wanted to share a little story that happened just earlier, probably an hour ago as of writing this. (I also play on PC for those curious)

I joined a public lobby and noticed that there was one red person (high mental state). I then saw this person kill another player who had I white icon. Assuming he was griefing, I paused and checked out the list of players to see this red person's stats. She (I'll use female pronouns since she's using a female character) is Lvl 100 with a 4 K/D ratio. I then thought "she may actually be a griefer" and so I tried to play hero and use guided missiles to mess with her (my spawn location was in the Kosatka, which was postitioned by Vespucci beach). I shot the missile and killed her, but of course after respawning she continued on killing the other guy. I did it again for 3-4 times but on the next one I noticed something.

As soon I launched the missile, I paused to check the map to see her position but I also noticed everyone else's icons disappeared. I quickly skimmed the top of the map (in the pause screen) and saw two other players there. Checked back the city and saw some player icons disappearing and reappearing except for me and the griefer so I just assumed maybe it was lag. Eventually my missile reached her destination, she was standing still by Pacific standard bank entrance so I got her with the missile. But right after that, I got up from the guided missile seat and finally the kill feed loaded. It said that I killed about 6 players simultaneously. I also saw a few messages saying "get out of here modder" and "leave modder". As soon as I finished reading those messages, my game froze then it crashed.

That's when I realized it all. That griefer may have been a modder and killed everyone. She may have been setting it up during my last missile launch, where she was just standing still. For those wondering, I also quickly checked my Socialclub account and saw my K/D went up from my usual 1.7-1.8 to 2.2 K/D. So those sudden multikills counted towards me and not that person.

If I were to guess, maybe that person used to kill everyone in the lobby using her IGN that's why she has over 4 K/D but after getting a reasonable amount of K/D she now griefs normally but will resort to using mods to mess with those ruining her griefing.

I don't know if anyone else had experienced a similar situation which is why I'm posting here. Unfortunately I have no other evidence (like video footage) except for this story.

PS: sorry for any grammar error, English is not my first language

TLDR: I killed a griefer/modder, who then proceeds to kill everyone in the lobby but placing the blame on me for it.