The people disappearing and reappearing is when they either quit or get DCd in front of you, making it look like they just got sucked into the ground. And then youll be fighting a bot and someone will join and that bot just vanishes reppaced by a full health bar player. They should make it to where if someone joins, they dont spawn in until next round.
I've barely had any. Either it is their own connection, region, or they are just dramatic. I'm in Mass and have relatively shitty wifi and have seen lag twice in game and despite issues that were resolved, no problems.
Since the new beta I've had no lag just sometimes randomly longer wait times for matches but nothing crazy