The phrase doesn't mean that masculinity itself toxic. It means that our culture's expectations for men hurt them and others. For example, the masculine ideal we hold men to is an expectation of stoic emotionlessness and self-sufficiency. As a result, many men feel a pressure to push through emotional difficulties, and feel a deep shame when they have trouble doing so. Some might even feel a deeper shame for seeking out help when they can't do it on their own, so they avoid involving loved ones and professionals that could help them. Men commit suicide nearly 4x as much as women do.
Toxic expectations for masculine traits permeate throughout society, too. A lack of sensitivity and tenderness is one such expectation, along with aggressive sexual promiscuity. This might lead some to view men as questionable caregivers, especially to children. Some men feel a pressure to avoid careers involving children, like teaching, which robs children of positive male role models. One can even argue that it robs children of fathers when courts prefer giving custody of children to their mothers.
Toxic expectations for masculine traits permeate throughout society, too. A lack of sensitivity and tenderness is one such expectation, along with aggressive sexual promiscuity. This might lead some to view men as questionable caregivers, especially to children. Some men feel a pressure to avoid careers involving children, like teaching, which robs children of positive male role models. One can even argue that it robs children of fathers when courts prefer giving custody of children to their mothers.