Ladybusiness' Gender discrimination in SFF awards has the hard research and numbers breakdown.
"This project demonstrates that SFF books by or about cis women are less likely to win awards than books by or about cis men. Trans and nonbinary authors do not win awards at all, and trans or nonbinary protagonists are extremely rare. Overall, there were more award-winning books written by cis men about cis men than there were books by women about anybody. While there have been recent gains in terms of diversity in awarded books, this is likely part of a cycle of gains and pushback that has repeated itself throughout the history of SFF awards. SFF awards have a problem when it comes to gender: they privilege cis men and the cis male experience over that of cis women and trans and nonbinary individuals."