alt Hacker Newshttps://www.en-hrana.org/day-twenty-eight-of-the-protests-ar...
This is the organisation most commonly cited in news reports, they estimate ~5200 protestors confirmed killed (+ a few hundred more for security personnel killed)
They are a group of anti-regime Iranian dissidents based in the US. I don't know why they would seek to provide a deliberately low estimate.
Confirmed != estimated. This source does not make any estimates. They are investigating every death individually. Given the lack of transparency, the true number of deaths is likely higher than the number which can be confirmed at this time.
As of writing this comment, the subtitle says "The number of deaths currently under investigation stands at 17,031." They do not claim that this is the total number of deaths either.
30,000 is not confirmed but cannot be ruled out.