My understanding is that its less about the word itself and more about the usage in contrast to how the same person refers to men. Males will be men, dudes, bros, etc. but they’ll only refer to women as females. Usually with a thinly veiled distain. “All these dudes just hanging out but the FEMALES are fighting.” or some shit.
I’m in my 30s and I’ve never met a single person in my entire life who refers to women as “the females”. I work in a highly male-dominated field full of country boys, for reference.
I’m in my 30’s and haven’t heard it out in the real world either, but that’s probably because the assortment of individuals who use females as a pejorative either don’t use it in public because it’s cringe and they know it, or because they don’t go outside.
That’s only my educated guess though.