Well it depends on the gravity of the misinformation right? Is it just a small prank or are you substantially influencing someone's world view? How grave are the consequences of the misinformation for the affected? How much distress does the misinformation cause them? I suppose there's always differences in degree.
Like the thing about the swedish scientists finding out a person ate like 20-50 Spiders in their lifetime while asleep, bc of spiders crawling into our mouths, which turned out to be fake news that was supposed to show how much easier misinformation spread if you just put the claim in that "scientists found out". Still many ppl believe it though.
So is it harmful to people who have severe arachnophobia? Is it just a funny experiment?