There a huge difference between what one thinks is misinformation, and what is proven to be misinformation though.

Epistemologically, yes. But for all practical purposes, at this point in time, there really isn't, since anyone can find sources that purportedly "prove" that whatever they want to believe is true and/or that whatever they don't want to believe is "misinformation." It makes absolutely no difference what the claim in question is - somebody somewhere online has "proven" that it's true, and somebody else somewhere online has "proven" that it's not.

So what that means is that to avoid the trap of endlessly dueling contradictory claims, somebody is going to have to simply decree what is or is not to be considered to be true - which sources and purported proofs are legitimate and which are not - and that's where it inevitably goes wrong.

And in fact, to go all the way back to the start of this thread, that's exactly how hexbear and ml work. They maintain their bubbles by essentially arbitrarily decreeing that [this] is true and [that] is misinformation. And if you press them on it, they're more than willing to post links to the "proof."