NO one seems to know what the “exact issur” is, and I wonder if there really IS an halachic issur (and if so, show me the makor). Are men forbidden to wear shirts sewn by women (sewing is considered primarily women’s work, even though there are men tailors)? Can they eat food prepared by women (ditto), and a myriad of other things that women do for men?
In my humble opinion, it is such a waste of energy for people to be bent out of shape and judge others based on the TYPE of kippah that they wear. My only exception to that statement, is if the kippah truly IS too small (if there is in fact a shiur to begin with), and if there is something offensive crocheted on it. Though a head covering is obviously important, what is INSIDE that head is way more important than what is covering it. Just my two cents’ worth.