How about just tying these checks to character traits like WIZARD/HERBALIST/SCHOLAR or whatever?
The problem there is that you'd be declaring that no-one who doesn't have those specific tags is allowed to know at all. That's far more unfair and unrealistic than being in a situation of maybe knowing, or maybe not having covered that particular detail in your studies.
It's weird, and it's not fun. I'm looking at a bright red glowing mushroom, in the underdark, with the name TORCHSTALK. What could it be?
It could be any number of things. Did you know, in advance, the very first time you saw one, what it would do? No, you didn't. You might, possibly, have made a guess, and your guess might even have been right, but you most definitely did not know.
How, pray tell, if your character has never heard of or seen it before, do they even know it's called a Torchstalk? You know it is, because you can read the nameplate. Those nameplates don't actually exist. Your character can't see them, or read the nifty tooltip that pops up for you when you highlight them with your mouse.
Even if they did; even if your character knows the name of the plant, perhaps it is named such because it's the best source of easy and safe bio-luminescence in the local underdark region, and safe to use as torches? Perhaps it's called such because when it's exposed to flame it burns continuously for an exceptionally long time? It's not a given what it does, and it's not obvious without experimentation... to work out whether or not your character knows something about it in advance, and can recall that specific information right now, without needing to experiment, we make a check.
Having high intelligence represents academic learning, and ability to recall order and collate information in your mind. There are many things you might know... you as a player don't want to have the task of pains-takingly sitting down to catalogue your character's entire sum of knowledge. Your character might know things that you, the player don't, because they actually live in this fictional world and you don't. Equally, just because you do know something about that world doesn't automatically mean your character knows it too. there's also the possibility that they do know something but can't bring the specifics to mind right now when pressed to - it happens. It happens less often to someone with high intelligence, who is by defintion better are retaining and recalling information.
If you don't want to make checks for these things, then the natural method in 5e is to rely entirely on passive checks - these are fixed values that require no die roll, that are checked against the DC of the task or activity. They're functionally equivalent to taking 10 on the die. Larian doesn't use passive checks in this game. They
Call some things passive checks, but they aren't. They're just active checks that the game makes for you without prompting.
In non-dangerous situations, where you have time or are not pressed, or there is no immediate pressure, you should never be treated as achieving below your passive - whether it's for knowledge checks, perception checks or anything else. For simple (pass/fail) DC checks, players who don't meet it with their passive but still might be in a situation to pass it might be offered the opportunity to make an active check, or they might simply fail, but characters who meet it with their passive should generally not be obliged to roll in those circumstances.