> Thank you for the heads up but I'm surprised "females" has become controversial. … When did the norms change?It is still not uncommon to see the word used that way in scientific text, official documentation, and data collection forms, though in those contexts the word male is probably near-by too so “female” isn't being used in isolation. Even in those places it is less common than it used to be.
Over the last ~decade referring to women as females, particularly in less formal contexts like discussions here often are, has become associated with incels & similar individuals/groups. They use it as a pejorative term, deliberately¹ using the technically-correct-but-unnecessarily-formal word as a way of distancing from women, suggesting they are a lower form², or blaming women for the unfair distancing the speaker perceives³. Then again they use almost every word as a pejorative term at some time or other, they seem to have a lot of negative brain wiring of which their attitude to genders may be but one of many symptoms.
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[1] and in spoken form making sure to pronounce the word in a way to make the intent obvious
[2] for a popular culture reference that might help: if you are a Trek fan, think how Ferengi characters talk about women
[3] “why don't these people I'm constantly bad-mouthing ever like me?”!