I think HP being as good as it is was because she wrote it during a time where she was less of an asshole. I'm still reeling at how a story like that could come from someone like her. Maybe stardom changed her, or she didn't have as much hate in her when she was writing it
I would hesitate to say "JK used to be good but now she's bad" because...well, Goblet of Fire was pretty early on in her career.
Rita Skeeter has a ton of negative trans coding ("mannish hands", she's hiding a secret about her identity, she occupies a villainous role within the story, etc.), everything to do with the house elves and SPEW (wouldn't it be funny if slavery is good actually, and Hermione wrongly(???) campaigned for equal rights), pretty certain there's some fatphobia with the Dursleys too, it's not difficult to draw a line from that to the present.
That said, I do think there's something to be said about her getting worse in recent years. Her rampant transphobia is clearly consuming her in a way that it didn't previously, because she's now writing multiple detective books about the subject. You can cut SPEW from a film adaptation because it's a relatively minor plotline, but I don't think a non transphobic adaptation of Troubled Blood could exist without rewriting the story altogether.
And of course, she wasn't openly politically advocating for right wing causes in the early 2000s, which is really the big issue nowadays. If she was quietly transphobic yet didn't act on it, that would still suck, but I doubt as many people would care - but she is actively making it everyone else's problem.