> But am I wrong? I'm constantly aware that Facebook puts me in a filter bubble. Does anyone have any good examples of left-leaning fake, conspiratorial news stories in the last few years?

I think most seem to be right wing, but the left has it's share. Anti vaxers, anti GMO, anti "chemicals" tend to come from the left.

I think your mistaking the causation too. They aren't conspiracy theorists because they are right wing, they are right wing because they are conspiracy theorists. When you think the government is doing all these bad things then wanting less government is perfectly logical.