They may have killed less people per year compared to Nazis but that doesn't make them less deadly. In terms of sheer human loss for society, they were 4 times worse than the Nazis (according to your estimate). If you consider how much freedom and how many lives they ruined with forced labour, it's even more egregious.
I've always considered Nazis and communists to be in the same bucket: authoritarian killers.
Communists often get a moral pass somehow, unlike Nazi and I wonder if it's because most schools and history teachers are biased; they teach about Nazi concentration camps but don't teach about gulags. I had to read books and books in school about Nazis and I didn't even know Solzhenitsyn existed.