Gale Johnson (1975):
For the entire twentieth century to the present, there have probably been between 12 million and 15 million famine deaths
As late as c. 1975, was the Great Leap Forward famine still not widely known?
When did it become widely known (at least among western historians/intellectuals)?
(Note: According to Our World in Data, the famines in 1900–49 alone killed 55M people, so Johnson's estimate above is wildly incorrect, even ignoring the Great Leap Forward. Nonetheless, his estimate does seem to suggest complete ignorance of the Great Leap Forward.)