Lol, what?
Black Book of Communism would put the figure at about 94 million for the twentieth century, and there's arguments that the figure is too big (although Communism would still sit at killing tens of millions of people.) " Upwards of 200 million killed by just Mao and Stalin" is absurd.
On the other end of the spectrum seven million by Hitler just counts the Holocaust. The number is quite a bit bigger when you include genocide against other groups such as the Romani or Slavs and purges of other "undesirables." Holocaust Museum on their FAQ page also seven million Soviet citizens, three million Soviet prisoners of war, 1.8 million non-Jewish Polish civilians, between 250,000-500,000 Roma, and 250,000 people with physical and mental disabilities. It's also worth noting Hitler was stopped in his tracks, while Stalin and Mao got to carry out their visions. If Hitler actually got to keep Eastern Europe and carry out his plans for a Lebensruam maybe he would have hit that hundred million single-handedly.
its more than arguments, the black book of communism is entirely discredited, even a co-editor calls it out lmao we should be thankful every day for the Red Armys efforts in defeating the fascists