(This isn’t related to any specific disinformation campaign – sorry if it’s off-topic for this community.)
In short: people mostly get false information from people they do not know very well. And, oddly enough, they are more likely to believe it than if they were given that false information from someone they know well.
I’m not sure if there is much here that is actionable by fediverse users, but it’s probably good to know about. Especially if you’re in a community that is mostly made up of people who only distantly “know” each other, rather than having more frequent, personal interactions with each other.
Here’s my guess based on no research nor expertise: y’all know which of your friends typically have good info and which are ‘full of it’ so you don’t believe the latter group when they repeat stupid stuff. Then when you hear from other random sources, our lazy brains don’t bother adding a ‘source?’ flag unless/until that source has burned us before.