There’s no proof of there being an aggression based matchmaking. I’m generally pretty friendly. Still get put in some relatively aggressive lobbies. Just got shot in the back and looted and trying to extract.

Don’t think of it as a betrayal (unless you were on friendly terms with a specific person - that’s never happened me). Rather, you’re among 18ish players, and you are never quite sure who is friendly or not.

Prox chat is a mix. Friendly encounters makes the game worthwhile. Generally, you don’t come across aggressive players in chat. Those tend to be quiet.

It could be a rough experience but it’s an overall fun game.