That said, I'm sure the death count numbers from the Rasht Massacre are staggeringly higher than the initial tallies of 2-5k.
Given the veracity of the current administration, the repeated history of the US government lying to justify military interventions (Vietnam Tonkin Gulf incident looks fake going back a little further), I think people who know a little bit of history and are paying attention have legitimate reason to want more than just one source. Whatever the number is in Iran it's terrible but there's no military intervention outside countries can do that's going to change that given Iran is already sanctioned to the gills and it's a huge country that presents many challenges - the people there are going to have to do it themselves.