It's a lot of different factors.
We eat crappy foods with hormones, plastics and estrogen. Our foods are often stored in plastic containers and many plastics harm men's testosterone levels.
Our water supply is contaminated with estrogen due to women pissing out estrogen from their birth control pills. Since modern foids are slut whores they all use birth control. That's a lot of estrogen in the water supply.
Our society is cucked in general and it affects men growing up. If you're fed liberal propaganda and feminism from young age, you're going to grow up to be more feminine and beta and you'll potentially have lower testosterone.
Lack of meaningful physical exercise/work and high body fat percentage is another reason modern "men" have low testosterone.
All of these things mostly only negatively affect men, but some of these hormones and chemicals also increase female testosterone which is why tall women with big square jaws are becoming more common.
"Manfaces" with square jaws used to be very rare, but nowadays a lot of white women in particular have manfaces with big jaws/skulls and masculine features in general (fridge body, big bones, deep voice.) 50+ years, the vast majority of young foids were not only attractive, but almost none of them had these manly features.
