I disagree that the usage is "you are behaving like a woman", I would say it's more "you are not behaving according to your gender". Men are called it for not being masculine enough, for being perceived as cowardly or weak, while women are called it for not being feminine enough, for speaking up for themselves or rejecting male attention.

i dont think most people associate it with behaving like a woman, at least i dont ever use it like that

if i hit my foot on something and say "you -idontwannagetbanned-!" theres no association with any womanlike behavior lol

same with like an annoying boss fight in a video game, i might call it that, not thinking even for a nanosecond that the behaviour is in any way womanly

i just use it as a more vulgar synonym for "annoying" really. i dont associate women with being annoying nor do i think that being annoying is a female trait. i would hope that most people think the same too but im ready to be proven wrong.

i hear the word relatively often from women who do use it against women too so in my experience theres not much of a case for it being a slur if the hurt group uses it as often or more often than others