Nope.Authors was partially former leftists,which downsized number of commie victims.Are you getting your numbers from the black book of communism? Because that's the only way you get those numbers. And the black book counts stuff like nazi soldiers as victims of communism (or more recently, covid deaths!?). So kindly get out with that nonsense.
From "The communist holocaust and its lessons for the 21th century" by Philip vander Elst.And Alexander Yakovlew estimated that Stalin alone genocided 60-70 millions.
P.S if you question numbers of victims killed by comrades Lenin,Stalin,Mao etc - then why not question numbers of victim of comrade Hitler,too ?
He was as good genocider as other leftist.