I've been noticing a lot more hostility around giving and receiving advice lately myself. I'm not sure if it's due to me playing on Dynamis a bunch the last month to get together with friends and the culture is different from Aether or if it's just a lot of new and returning people to the game, but here's my strategy. We're going to use World of Darkness alliance raid as an example as it's a place we all get sent to a lot.
We're fighting Angra Mainyu. Either two tanks are fighting for aggro and spinning the boss around, or no tanks have stance on and aggro is bouncing all over the place, causing the laser beam blasts to hit everyone else. I'm not going to say anything at first--I want people to be able to assess the situation and determine how to fix it for themselves. Honestly I usually won't say anything unless we actually wipe--even with a scuffed run most of these Alliance raid fights are still easy enough to clear if there's enough people up and attacking the boss. If we wipe, I may put something in chat like "Let's keep the boss facing north to control the lasers" or "I think we missed one of the adds. Make sure to kill any additional enemies that spawn."
Even if one person is clearly the one messing everything up, I never call them out on it directly. I just try to explain the mechanics like I would to a friend who's new to the fight and a little unsure. Calling someone out directly is only going to make people defensive, and especially on casual content like alliance raids, it's not the end of the world if people mess up and die a lot, chances are everyone can still clear just fine and it's not worth getting upset over.
Granted, even with this strategy, I've had a few people get super defensive and pissy anyway. At that point I just disengage and block them because if someone asking nicely in group content to please do something very basic like tank the boss, accept a raise, or heal anyone ever is enough to piss them off then they're just being childish at that point and are not worth my time.