I don't have an in-depth understanding of the evolution of the movements so my impressions are based purely on how I've noticed the more casual discourse change over the years, i.e. before trans activism vs after. All the problems with liberal feminism look like your average pandering to horny ""devil's-advocate"" male liberals, and that results from the usual socialisation putting male misogyny above women's rights and dignity. Liberal feminism has been problematic way before trans ideology started taking centre stage, and most of its problems needn't involve trans ideology at all and are more easily explained by wanting to (often literally) sell women a safe, mainstream version of feminism that won't get their boyfriends pissy, where everything is fine as it is so long as you yell "girl power!". Perhaps it's a result of said "girl power" becoming a popular thing to market to girls in the...what, 80's? 90's? already rooting in the mind of little girls a pandering, male-approved popular image of feminism. Also I'm sure their messaging about how women are just as strong as men is a huge factor in so many people supporting men in female sports.

Feminism can't really hold a candle to the patriarchy as far as societal influence goes, so it can't give women value when the patriarchy keeps beating them into the ground every single day since childhood while giving them the easy "just be pretty and you will be loved" solution. Women who are socialised all their lives that the only worth they have is their femininity, with a plethora of accompanying trauma and anxieties (by design), aren't just going to reject that, even when they're aware of how damaging it is for them. The mere implication of making women reject femininity still gets shouted down as extreme, because that would make them lose the only value as a woman in a world of men, the only ability they have. So liberal feminism sells women the idea that they can have both their cake and eat it too: they can be beautiful, feminine and (insert everything else that society discourages or punishes women for). So their only form of societal worth is preserved while also acknowledging the unjust elephant in the room that the pesky feminists keep bringing to their attention.

Most men are bioessentialist, and that applies to liberals. They're going to want to hear that women endure their trauma because their brains evolved for it, much like how they'll want to hear that women deserve male abuse and discrimination for the same reason. To get their support, liberal feminism must somehow pander both to liberal male supremacist ideology where female submission and suffering under men signifies male freedom and a proper, natural world order, but also it has to sell women the idea that this suppression is empowering and something they freely choose for themselves (which also lets them kinda skirt around the bioessentialism because oppressors' victims don't like hearing that it's in their biology to be oppressed as much as their oppressors do). If you can do that, you can not only sell a much easier, status-quo-appealing form of liberation to anxious, traumatised women clinging onto their only form of worth, but you can even turn this plight into its own struggle for justice, justice for femininity, the real victim of oppression. It's not unfair that women are subject to all this crap for having the gall to be born female, but rather, the real injustice is that femininity (focusing heavily on sexual submission to men, both to make it more appealing to them and because that's the reason femininity exists in the first place) has been so unfairly marginalised and isn't seen as strong and empowering, to the point of vilifying women who reject femininity as suffering from "internalised misogyny" and being bigots against "sex work", swerfs akin to racists. Now traditional women can feel powerful for doing what they're pressured into all their lives because they can tell themselves it's all an intentional, wilful act of defiance and empowerment on their part. This also plays into society constantly calling women "powerful" for men being horny and wanting to fuck them. Men ofc love hearing this, because to them, it's all the usual confirmation of ladybrains and the proper world order, but one that makes them sleep better at night. It goes without saying that women are choosing their oppression, because women have evolved to be oppressed by men and to enjoy it. It's not a result of men being awful, and now they can even call themselves feminist for jerking off to porn stars. They're encouraging women's self-expression and freedoms, helping them accept themselves in the modern world pushing them farther from their true, natural role.

Trans people saw this, and swooped in: the silent, implied bioessentialism was perfect for revitalising the concept of ladybrains in feminist movements, and femininity as the real victim is what makes a man with she/her pronouns equally as oppressed as a woman. Once you make gender oppression be all about freely-chosen femininity, why couldn't anyone choose it and become a woman? In fact, wouldn't the men choosing it be the most oppressed of all? Doesn't anyone ever think of men and their oppression?

Also, liberal feminism's "sex-positivity" and "no kink shaming" is the perfect breeding ground for ideas like an anus being equivalent to a vagina and fetishistic men being the real victims.