I don't know how to define what is "misinformation" but I could surely call out a couple examples. Maybe we can figure out what makes them misinformation.
1) 5G causes COVID-19
2) COVID-19 doesn't exist, i.e. it's all a hoax
3) Aquarium cleaning solution is a cure for COVID
I don't know what makes those different from "masks are worthless" but they seem qualitatively different. Maybe for a couple of reasons.
Maybe for #1, there's no plausible mechanism of action linking 5G and covid. But the people claim there is! Using a nested series of faulty reasoning and unreproduceable evidence to back it up.
Maybe for #2, there's no observable evidence that it's a hoax, i.e. people claiming otherwise are doing so with no supporting evidence, only reasoning that they (subjectively) do not trust government or media, therefore their claim is supportable.
But I don't know. I don't think the answer is that it's unknowable (which you may or may not have been getting at).