Every time a Harry Potter video is posted on YouTube or Facebook -- not exactly bastions of liberal thought -- it's brought up.
The "no one has heard of a controversy everyone has heard about" discourse around here is crazy.
You are approaching it from perspective of anglosphere, probably from USA or UK. Personally, i read portals, regional ( from SE Europe), Italy, Austria and Germany. Italian portals for most part ignore anglosphere all together and focus on internal stuff. Austiran and german portals, they are mostly academic and detached and news about Rawling were buried in subsection of Culture. It wasn't on main pages. That specific subject that makes her stances controversial, isn't that big on news portals across continental Europe, at best, it gets article in one of the subcategories that least read, Culture. Also, on Facebook, news from Culture have abysmally low reach.
That's more on the general side. On more personal side, people just grew up. Last movie came out 15 years ago. By the time she started spewing her stances on twitter (very USA centric social media), people stopped caring about her, at least casual fans did. They grew up, developed new interests. Majority of that verbal dhiarea came during covid. We were between lockdowns, most of older fans were dealing with grown up problems, news were flooded with other, more important stuff.
Anecdotally, from people at work and in social circle, was majority really doesn't know about her stances. They grew up with books and movies, but are now people in mid to late 30s, with kids, jobs, families, mortgages. At best, people knew she said something controversial, but don't know precisely what and don't care enough about her or her personal stances. HP is part of childhood, they will probably watch new stuff for pure nostalgia sake, but don't care enough about author. Hell, i needed to google to see what she was talking about precisely. Maybe because most of them moved away from social media years ago or have heavily curated news feed on FB.