I find this fairly astounding. The typical stay-at-home parent is the mother and while it's getting closer to parity I don't think it's anywhere near even. For that reason alone I would expect more men in the work force. What are men doing if not working? On disability? Homeless? Retiring earlier?
Some are being "proprietors, private household employees, unpaid volunteers, farm employees and the unincorporated self-employed." From a link somebody else posted https://www.stlouisfed.org/open-vault/2019/july/nonfarm-payr... Unincorporated self-employed sounds like tradesmen, laborers, and some kinds of professionals which is a lot of men.
"Nonfarm payrolls" was never meant to be a gender-balanced stat, it just excludes the hardest to track jobs. Which is fine for comparison over time, but makes 50% a meaningless metric.