"Led by German expert Stefanie Haustein, a group of scientists has now calculated the turnover of the “oligopoly” that controls this new market. Using mainly public funds, the scientific community paid the five large publishers $1.06 billion in four years. And according to this estimate, the sum covers only the fees to publish open access studies."

https://english.elpais.com/science-tech/2023-11-21/scientists-paid-large-publishers-over-1-billion-in-four-years-to-have-their-studies-published-with-open-access.html?ssm=FB_CC&fbclid=IwAR3SibNKGyOqW3YIqmJ0IVpRZPKkWs45khTZBgZFsMe0qILKyeKFFV8tnf4