Back in 2020 when JKR wrote her TERF Wars essay, I remember people reacted with surprise that she would hold reactionary views, but at the time I was surprised that they were surprised because she had held reactionary views for quite a while at that point. And while the problems with Harry Potter are quite well-known now, I realise that there are many other things that people simply aren't aware of, even many years later, either because they weren't around then or because they weren't paying close attention to her output at the time.
Her 2020 detective book Troubled Blood famously features a serial kidnapper/torturer/murderer who lures women into a van by wearing a wig and women's clothing, but that was hardly her first foray into transmisogynistic caricatures. In Harry Potter there was of course Rita Skeeter with her "large mannish hands" and Madame Maxine who is said to be "part-giant", but she got rather more explicit in her early detective novels.
The Silkworm was published in 2014, and it features a young, tall, trans woman called Pippa whose first appearance is an attempted stabbing of the detective, who warns her to be careful because she won't have a good time in jail since she's "pre-op". Pippa is upset because she has read a manuscript in which she is caricatured as a [H-slur] who believes she has a beautiful voice but actually barks like a seal, which she (accurately) interprets as mockery of her vocal feminisation exercises.
Her next detective novel, Career of Evil (2015) features a subplot around the "transabled" community (a group of people with what the ICD-11 would describe as Body Integrity Dysphoria). The detective, a war veteran amputee, gets very frustrated when he has a meeting over lunch with a rude and self-obsessed "transabled" character called Tempest. Tempest assumes him to be rich, orders expensive food and wine, and keeps interrupting everyone to focus the conversation back on herself. She is described as "able-bodied" but uses a wheelchair and disabled facilities and hopes to one day get her spinal cord surgically severed so her physical body can match her disabled identity. I don't know if she still does this, but JKR used to do quite detailed research for her detective novels, and I think it's not that far-fetched to speculate that this might be a twisted parody of a meeting she had with a trans woman when researching the character of Pippa for the previous book, certainly the "transabled" subplot seems a thinly-veiled reference.
It's not just her books though, her political attitudes more generally were always quite suspect. I lived in Scotland during the independence referendum in 2014, as JKR did, and while I supported independence, she was a very vocal anti-independence campaigner who also donated £1 million to the anti-independence campaign. It's worth remembering that JKR is an English woman who lived (and still does) in a mansion on a 12 acre country estate at the southern edge of the Highlands, something that has historical significance for reasons that I'll now go on a little side-track to explain.
England had been trying to annexe Scotland for essentially as long as the two countries have existed, and they were finally united in 1707. However, there is a separate-but-related dispute that ran in parallel to this one. Scotland was historically divided between Highland and Lowland, where Highlanders were mainly Gaelic-speaking (a Celtic language), often Catholic, and had a clan-based political system; while Lowlanders were Scots-speaking (a Germanic language), mainly Protestant, and had a political system much more similar to the English one. The Highlands were a major headache to the newly-unified British government in the 18th Century as a heartland of Jacobite rebellions (supporters of the descendants of deposed Catholic King James VII/II), which were a complicated series of wars partly about religion, partly about culture, partly about Scottish self-determination, and partly a vehicle through which Catholic countries like France could destabilise one of their colonial rivals.
After victory at the Battle of Culloden, the British government instituted policies that would destroy the Highland clan system once and for all. New laws were passed that made it straightforward for clan chiefs to retcon themselves as "landlords", an upending of a traditional clan system in which the hierarchical structure of land management had been not nearly so clear-cut, and where land had been considered a community asset administered by the chief rather than personally owned. Some chiefs were forced by debts to sell the land that they were suddenly legal owners of to wealthy English or Lowland Scottish landowners, who became the new landlords. In a genocidal process known as the Highland Clearances, these former clan chiefs or their English/Lowland replacements kicked their clanspeople (now considered "tenants") off their land, burnt their houses to prevent their return, and turned the land over to a profitable sheep-farming monoculture. British laws banned Highland cultural artifacts like tartan and bagpipes, and the use of the Gaelic language was discouraged. The extent to which is this is direct English colonisation is debatable, it is certainly a case of the English government empowering Scottish aristocrats to do their dirty work for them, the main English priority was preventing further uprisings. But colonisation-without-much-settlement via enforcing cultural alignment with England through bribery of local leaders was a classic method of the British Empire, and I think it makes sense to view this as one more example of it, with the Highlanders specifically as the victims.
It's worth noting that the viewpoint of Scots in general as net victims of colonialism is not accurate. My own ancestors were forcibly dispossessed of their land in the Plantation of Ulster by mainly Lowland Scottish settlers who were empowered to do this by the legal backing of the (English) government, instituting a major wealth gap between the Irish and settler populations in this area that still exists today. Many of these Scottish people soon moved on to refine their settlement skills in North America: they are the ancestors of the Americans who today refer to themselves (with pride, for some reason, that they are descended from people who were settler-colonists twice over) as "Scots-Irish".
Furthermore, one of the principal reasons for the 1707 union of England and Scotland was a failed attempt to establish a Scottish colony in the famously-hard-to-traverse Darién Gap (at the modern-day border between Panama and Colombia), an early version of the Panama railroad/canal projects, in which it was planned for the settlers to administer the overland transport of goods between ports on the Pacific and Caribbean. There was also a plan to bring slaves (presumably from West Africa) and work them to death in gold mines in the area. The scheme was a complete disaster, in part because the English government refused to provide any assistance, including denying Scottish ships the right to dock in Jamaican ports for resupply. The majority of settlers died and the scheme bankrupted a huge number of Lowland Scottish families who had invested in it. The 1707 union with England was partly motivated by a desire for England to help refund these losses. This is often talked of from the point-of-view of English harshness towards the Scots, but that really elides the context that the Scots in this case were literal colonists of stolen American land and only their own failure prevented them from directly partaking in the trafficking, torture, and murder of Black people from West Africa. After the union with England, Scottish people became active participants in the new British Empire, and any suggestion of ontological Scottish innocence of British crimes after that point is nonsensical.
So that's the context of Scotland as both perpetrator of colonial crimes (on the Lowland side primarily) and also victim of them (on the Highland side primarily). The English are not generally regarded with particular positivity in the Highlands, although mostly this takes the form of light-hearted ribbing with an undertone of genuine frustration. JKR's country estate is right on the boundary between two historic Highland regions, Breadalbane and Atholl, both of which have their own grim tales of Highland Clearances resulting in mass depopulation of their respective areas. The fact that her house, Killiechassie, has a Gaelic name tells the tale of a culture that was once present, but finding a Gaelic speaker in that area today would be very difficult. To be clear, I don't think it's immoral for an English person to live in the Highlands, but I think there is a duty to be aware of the history of how your country caused what was effectively a genocide of a local culture that is now seriously endangered and whose historic land you now live on (in spite of the essentially Orientalist attitude to the Highlands in English society today, that is at once fetishistic, paternalistic, and ultimately hateful). For such a person to not only vote to deny Scottish people their independence, but also to fund the campaign to prevent that independence with an amount of money that would be totally life changing for anyone else in her local area, seems like the epitome of a settler-colonial mindset, even if framing it that way sounds odd at first.
It wasn't just her funding of the anti-independence campaign in 2014, which was bad enough, but I remember actually being more surprised by her Twitter posting. There was a pretty regular cycle where an anti-independence rally on a Glasgow shopping street would attract maybe 20 people, and they would then get heckled by loads of pro-independence passers-by, predictably portrayed in the mainstream press as "violent pro-independence mob harasses poor innocent elderly people just going about their day in peace". JKR was a keen spreader of this propaganda, and would decry the mob from the safety of her country estate. She would say stuff about feeling unsafe as someone with an English accent with this kind of mob violence going on, that English people were now oppressed for being English, that she had thought Scotland was supposed to be welcoming to immigrants but given how they treat English people she is concerned etc etc. It was essentially the cardboard monsters meme, but it really set the tone for a future of self-victimisation-as-politics, where someone near the top of the social hierarchy feigned that she was at the bottom of it in order to prevent the liberation of those actually below her.
In 2015, Jeremy Corbyn was elected leader of the UK Labour Party. I think its fair to say that, for all his flaws, he was the most leftwing leader of any major party in UK political history. And JKR really didn't like him at all, which is not surprising since he was a socialist in favour of intense wealth-redistribution and she was a billionaire. Her propagandising really took off from this point, and she would retweet anything, no matter how vague and unsourced, about his supporters' violence, just as she does today with any pro-trans figure she encounters. Self-victimisation really became her watchword, and she would position herself as a poor harmless liberal centrist being hammered by fascists of the right and left. Any hatemail she got would be shared as representative of the unhinged violence that would be let loose on everyone if we let the radical left win.
Which is to say, the JKR of today is pretty much exactly the same person she was in 2014-2015. She was an English settler in the Highlands who used her vast wealth to keep Scotland perpetually tied to England, and she framed the frustrations of Scottish people towards her as the victimisation of a poor innocent baby hated by an unthinking mob. She had clearly made up her mind about trans women many years before TERF Wars, and her attitude on that issue, casting herself as a perpetual victim incapable of actually doing harm in order to get away with the material harm she does, is exactly what you would expect given her attitude to everything else. I think some people are radicalised into transphobia, but others are already there, and they just need to be told about the existence of transness for their pre-existing political views to expand and fill the new gap.