I feel like sometimes people refuse to “meta game” in a way that is also metagaming, except targeting bad outcomes instead of good.
Like your characters live in a world with trolls. They’re not a secret. Choosing to intentionally avoid fire because “that’s metagaming” is also metagaming. You’re using your out of character knowledge (fire is effective) and then avoiding it.
Usually cleared up with a "hey dm, what are common knowledge and myths about this stuff? or whatever.
I don’t have the players actually make the stealth roll until something opposes it. They’re doing the best they can. Here comes the guard. Roll, please.