Historical numbers vary, but I recommend checking historians using data from after the opening of the Soviet Archives. I also wouldn’t count Pol Pot as a genuine Communist leader, and not out of any “no true Communism” nonsense, he legitimately denounced Marxism and had a form of “Communism” utterly divorced from the Marxist canon.

One thing to keep in mind is that extremely frequently, deaths due to natural forces like drought-induced famine or otherwise are counted as “excess” deaths, which is a dishonest framing. No genuine Marxist would say there were no excess deaths in Socialist states, such would be taking an idealist analysis that infantilizes the genuine revolutionary struggles faced internally and externally by the Proletariat.