A perfect example. Early "conspiracies" like bloating the numbers by counting anyone who died "with COVID" as having died "from COVID" and the disease having come from a lab due to gain of function research appear to have been borne out, among many others, too many to count, that ended up being bullshit.
That was a perfect storm of misinformation and disinformation that is still being pored over to this day.
Another good example is 9/11. People who refused to believe that steel infrastructure could not be damaged to an extent that it would implode and collapse into its own footprint - even if it wasn't hit by a plane at all - were labeled "truthers". Whatever you believe about 9/11, it's very difficult to look at it in retrospect and not admit that something very wrong happened, and many questions are glossed over or left unanswered.
Labeling something a conspiracy immediately causes people to recoil lest they be categorized as tinfoil hat kooks, but the idea that powerful people will do horrifying things for their own interests under the thinnest cover and get away with it is not new.
That said, it is far too easy to lose grip on reality and start seeing everything as a conspiracy, so it's always advisable to hold truths lightly, and examine them frequently. Hand waving things away with "they" statements is the worst kind of intellectual laziness and doing so is a great disservice to oneself.