I wonder what causes this. I don't think there's an effort gap anymore because men are as neurotic about looking good as men now (every man has a skincare routine, every guy joins a gym at 16yo).
I think it's just social perception of sexes honestly. Women are represented as beautiful much more often than men in media, men are not sexualized nearly as much and when they do they're usually sexualized for gay men rather than straight women. This and considering feminine beauty the beauty standard for actual centuries is probably caused a perception of men are pretty men are ugly.