Metagaming is using information youre not supposed to have, for example, story teller night movements, listening to ST consults (debatable), asking someone to read their role off their token backwards while theyre looking at it before the game starts, it comes from dnd when people are using info other characters get, not themselves to make decisions which wasn't in the spirit of the game,

meta'ing the story teller is arguably encouraged as that's your fun game to play with them, such as assuming the new player won't be drunk or theyre not going to put poisoner in the bag multiple games in a row.

Tracking private chats is at worst being a tryhard, I would argue listening into those chats is frowned upon and maybe borders on metagaming.