I'm not even so sure it's PVP, itself, as a blanket thing, but rather how PVP is organized and run within the game.
For example, when I played WoD games, it felt like the prevailing OOC opinion was that PVP had to end in the destruction or utter submission of one of the parties involved. I think there were even arguments on WORA at the time from pretty prominent players that there was no OOC reason to leave an IC opponent in any position to ever be able to fight back against you - which usually meant killing them - no matter how minor the conflict...because if you did, the OOC assumption was that they were going to get their revenge and destroy your character, and you'd kinda deserve it for not taking them out when you had the chance.
Which did seem to play into an OOC atmosphere in a number (not all) WoD games I was on that, no matter how rare PK was in practice, you always had to assume that any conflict with another character was going to eventually end in your PC getting ended unless you 'got there' first, or managed to make the PC largely invulnerable. So there was a whole lot of IC and OOC posturing about how tough your PC was, how well connected they were, how sneaky/assassiny they were - any sort of 'protective coloration' people could find to put out there. And when conflict did happen, people tended to assume 'this asshole is trying to end my character' and respond accordingly, IC and OOC.
Now, those are only my observations. But possibly the least toxic game I was on was Requiem for Kingsmouth, and I think part of that is because the methods of PVP explicitly expanded beyond 'murder the fuck out of that guy' and had interesting and satisfying mechanics for fighting for territory, etc. (Mechanics that I believe were adapted from LARP rules? Which was a good decision, I think.) There were also some notable de-escalation points of PVP, and reasons to spare people (you could grab a boon from them instead, etc.).
I'm not saying RfK was perfect. People still threw shit fits about stupid things, and there was certainly bullshit on the micro and macro levels. But it's one of the games that really tried to engage with wanting to facilitate a specific TYPE of PVP, and making sure that the mechanics made that feel powerful enough to draw people into using it, without having an end game of 'kill your enemy'.
I've come around to thinking that if you're going to have a game with PVP, you need to be as explicit as possible about the mechanics of those conflicts, open about potential consequences to characters at each level, AND build in 'de-escalation' points along the track that ICly and OOCly incentivize being a gracious victor and not pursuing an opponent's utter destruction.