It really really rubs most of us the wrong way. Yet, for whatever reason, stupid men are taught that it is ok to call us "females". It is like we are corpses. Things. Not even people.
Even if someone called me a "male" constantly it would kind of freak me out. They are theoretically interchangeable, but male or female just comes off less "human" I guess. If they choose to only ever say male or female then it makes you wonder if they literally perceive you as inhuman.
I mean I used to do it tons in the army, that was the accepted way to refer to the women. Like "hey where is the females bunk I need to drop something off to sgt jones"
I never meant it disrespectfully, can't speak for anyone else though.
It's not so much that the word itself is offensive it's just that using it as a noun instead of an adjective to refer to a person carries with it connotations and implies you're referring to a person as if they're a subject or an animal or something below human.
At the same time we call children “human larve” and everyone is ok with that
In Low Saxon (and Northern German) there's "Schietbüddel". Depending on how you translate it it could mean "chaotic/sticky minion" or "bundle of excrement".