Yes. It’s so annoying. A lot of good roleplaying is imagining a way your character would have/know something. Obviously you can take it too far, but it’s an important skills for keeping the game moving. Like, say one character is obviously falling for some sort of trap by a doppelganger. OOC you either know or are suspicious, but IC you don’t. You want to go with them so they aren’t alone. But you can’t just say that. Say something like, “I’ll tag along, I’m getting stir crazy and could go for a walk.” It’s technically metagaming but it’s a very different situation than doing something like telling that character not to go because the other person is suspicious when you genuinely have no reason to think they are.

Another good example of metagaming that so many people view as okay that they don’t even view it as metagaming is telling your party OOC how many hit points you have remaining the healer choosing who to heal and with what spells based on the information. Your character doesn’t know that number. A lot of times all you really know IC is if someone has less than half of their hit points remaining and a vague idea that barbarians can take more hits than wizards.

Obviously there are scenarios where this doesn’t hold but I find in general that metagaming which benefits everyone, doesn’t completely ruin encounters, and is done with an excuse that your character would actually reasonably do is typically okay.

Another example. I remember in one game we were trying to open a creaky rusty door quietly. Someone asked if anyone had oil. We all checked our inventory and nobody did. He explained that my character in heavy armor would likely have some because regular maintenance of it would require that. Which seemed fine. The DM agreed. So my character hands his character some oil.

That’s true. I also often got:“My character is actively avoiding every other character as well as engaging with the multiple plot hooks dangling right in front of them, because they have a busy social life, a day job and are naturally suspicious of anything new. No, I want to play. It’s just what my character would do.”

That’s also a kind of almost metagaming, because they know, as a player, that they can only pull that crap, because another player or the DM will have to do all the extra work of bringing the party together and on track.