FaZe effect

A phenomenon observable in most online video games with competitive matchmaking and ranks, in which random players tend to be far more abrasive and uncooperative than those you meet in casual drop-in games or community servers, even ones hosting games in competitive format. This is counter-intuitive to the assumption that less mature players will be deterred by the stiff penalties for ruining matches, which turns out to grossly underestimate how consciously dedicated some people are to being awful.

There are a variety of reasons for this, not least of which is because clueless kids think they're going to be MLG esports pros and thus blame anything that goes wrong on you, regardless of how well anyone is actually doing, and frequently ragequit, leaving you unable to pick up the match. In higher ranks and tiers, it is common for players to not care about playing because they think too highly of themselves, while many players in lower ranks are using smurf accounts so they can grief newer players trying to git gud.

Named after FaZe Clan, a (real) professional esports team that many of the aforementioned clueless kids like to reference in their screen names.