Plenty of systems have something for that, often with a variety of options.

A bookish Exalted character might roll Intelligence + Lore to remember having learned about the weakness to fire before. Or maybe Intelligence + Occult if the weakness is supernatural in nature. A combat-oriented character might roll Wits + War to deduce that fire is needed based on the knowledge of old battle reports involving trolls. Maybe even something involving Survival if they're familiar with a region trolls can appear in.

A game with a flexible skill system has a lot of room for such things.

Without looking it up, I'm fairly certain that Arcana, Nature, and maybe even Survival checks can all be employed to fill this "character knowledge" confirmation, and have always been used for this and more. 🤦🏼‍♂️

There's more than the two alternatives of playing "Myself, a person who games a lot and knows things a veteran gamer would know, but with D&D powers" and "The personification of chaotic stupidity that is my alter-ego, an insufferable piece of shit, but with D&D powers".

The "My Guy" syndrome is the inexperienced person's experimentation of Improving in RPGs. The meta-gamer is the experienced-but-tactless person's desire to play the game straight up as a board game, rather than a social experience.

There's a third - even more experienced - kind of player, who can seamlessly integrate the rules they're very familiar with into the story of their character that they're trying to tell. The player who says "I'm going to play a kleptomaniac Rogue" and proceeds to steal the belt off a rampaging Ogre to trip him with his own pants as a combat maneuver. Or the player who says "I'm going to play a Stubbornly Self-Righteous Knight" and is as rigid in his morals as he is tankie in his ability hold the line when the party needs it most.

These players lean into their conflicts for a comedic interlude, then squad up to form a deadly duo when its time to crack heads. And that makes the game both more fun for everyone at the table (especially the DM) than someone mired in the technicalities of a feat description or obsessed with being the center of attention.

My guy syndrome?

they turn to stone when exposed to sunlight so wouldn't it be logical to think fire might turn them into stone?

Is this meta- metagaming?

slightly neurotic diviner who almost always knows what's optimal, and struggles between doing the obviously ideal thing or rejecting that and knowingly doing something suboptimal so they aren't just a puppet to the magic

My tiny tortle sorcerer is obsessed with putting gems in his mouth. The DM knows this. The party knows this. It makes for some very funny conflicts