If someone brings up AGAB out of nowhere they most probably have TERF . Of course it has it's place but it's a term that denotes what you get assigned at birth. People try to use it as a woke placeholder for "biological sex" instead of just writing out what they actually mean and not folding it all into a faulty concept. For example I see it used, sometimes even by trans people, when referring to things like how someone got treated while growing, what hormonal profile they have/used to have, what genitalia they have... Most ridiculous example was AFAB-only housing, which just meant "I'm scawed of twans women owo, not allowed in the womb woom.".