https://www.theatlantic.com/education/archive/2018/09/why-gi...
Boys read for pleasure much less and apparently don't read as well as girls when they do: they use less challenging books and skip/skim more. In general somehow reading has seemed to grow more gendered over time; if you go into the average chain bookstore its apparent that its heavily targeted towards women, and something like Amazon's free Prime reads are often almost entirely women-targeted genre selections.
Young adult books for example are targeted almost entirely towards teen girls now, and even manga or comic books seem focused on the female market in increasing amounts.
Jon Scieszka, a kids author, noticed this over fifteen years ago and started guys read, a website trying to encourage boys to do so and raise awareness about it. But it seems to have stalled, and I don't hear a lot of talk about the feminization of reading.
I really think that this is a major part of why boys fall behind. Reading in general is the basis of learning, and boys over time have moved away. There's always been cultural resistance against "book-larning" but its weird how gendered reading itself has become lately.