In addition to the obviously just transmisogynist takes, it also feels to me like Jax is yet another example of people saying how much they want "complicated, nuanced, and morally grey" characters, and yet when they get one they immediately start trying to fit them into a black-or-white framework. Like both "Jax was just a super sad babygirl that did no wrong and it was all everybody else's fault" and "Jax was an irredeemably evil super abuser that deserved to everything bad that happened to her" are both objectively incorrect readings of the text, yet I've seen so many people taking these stances. Jax was a complicated character who's paralyzing fear of being honest and vulnerable about who she really was motivated her to do some truly awful things, but she was also someone who did really care about the others and even put herself in harm's way in order to help them, and they all cared about her as well, even when her reflexive bullying-to-push-others-away made it difficult to do so, as evidenced by how many times they all tried to reach out to her and were visibly horrified when she essentially killed herself. It was this complicated nature that made Jax and the other characters' stories so compelling to me and I guess I'm just a bit frustrated that so many people seem to want to scrub away all of that nuance.
People say they want morally grey characters because it sounds correct. It's not what they actually want.
Malcolm Gladwell has given talks on this: People know what they want, but they don't say what they want. Coffee was always his famous example. Focus-tested coffee buyers say they want a rich, dark roast when asked what coffee they drink. Listening just to focus groups, consumers want a rich, dark roast.
However, when buying habits are observed it's found instead the average consumer buys a weaker, milkier coffee because that's what they actually wanted.
This was the same thing with that whole "nuanced villain" schtick a decade ago. Everyone swearing up and down the garden path that the best villains are the ones who are nuanced, and probably don't see themselves as the villain.
However, the villains that actually became SUPER popular during that same time period? All of them were over the top evil villains. You can have all the nuanced writing in the world (they never did but still) but the audience responded much more favorable to "NANOMACHINES SON!"
A big part of this is, admittedly, that this supposed nuanced writing never materialized and writers often fell back on boiling kittens in lava.
So when people say they want complicated, morally grey characters... no they fucking don't. They never have. You can see the pattern in fandom spaces of people losing their minds the instant their pwecious uwu baby boy does anything bad. Look at how people reacted to Aang being a bad father. Not even an abusive father, just a mediocre one who had a clear favorite.
People want their characters to be squeaky clean good guys, or irredeemably evil villains and if you give them anything else they will complain and then filter that character into one of those two boxes based on their pre-existing biases.
One of the big reasons I was railing so hard against that "Abused becomes Abuser" trope is because I knew people didn't like it because they appreciated the complexities of abusive victims and their psychology, they liked it because it framed killing the abuse victim as some kind of mercy, like George killing Lennie.
It reinforced their belief that victims of abuse are fundamentally broken and forever tarnished, and frames it as a tragedy. It's right there in how they talk, inflating the statistics of abuse victims who go on to abuse others from "rarely" to "most."
This is why stories about "bad people who do bad things" have gotten so irreverent and over the top lately. It reinforces that binary and removes any guilt for enjoying it because "I know they're bad people."
They don't want the story to change, they just want the same thing they've always had but framed in a way that sounds more nuanced than it is so they can feel smart. If you give them real nuance, they'll complain because real nuance doesn't give them a blank check to hurt someone, or fawn over them incessantly.