For what it's worth, I don't think the castbar determining if you were in the AOE or not has anything to do with the netcode (except for the fraction of a second at the very end if you're trying to greed, or just have awful ping). As Jinglypockets said, the netcode in the game is definitely subpar, but being able to go into what was an AOE right after the castbar finishes isn't netcode, it's game design. Maybe it's game design to get around a different netcode issue, but it's not directly netcode related. It is counterintuitive and a little obnoxious to get used to, especially when some of the animations can take a couple seconds in some of the flashier fights, but once you adapt to it it's hardly noticeable and feels like second nature.