I noticed this when all the hoes would all ways have good grades . To make sure I waited high school and even during graduation it’s always more hoes graduating
School and university is a lot about fitting in, being concientious, learning and repeating, being still and self-controlled. It's also dominated by females (especially teacher and amongst those especially teachers in elementary schools IIRC). There were also studies showing teacher bais dragging down boys in STEM subjects because they wanted girls to be more equal.
In general, boy have a higher variance in traits. Meaning they have more geniuses and more idiots. School caps the upper level, meaning if you are a genius, there is a limit to what degree you can express that. Get the highest grade and that's the end. If you could do more, you will have to do it on your own.
Everytime you put a limit on the lower end (e.g. you don't include homeless and mentally deficient) you raise the male average more than the female, and everytime you put a limit on the upper end you do the opposite, lowering the male average more than the female.
In America universities are also increasingly putting a focus on ideological homogeneity, which is easier for women, who go along with w/e is society tells them to by default. The list goes on and on. School is not a great palce for many boys, and it does not nurture exceptional talents found disproportionately amongst the male population as well as it should.