Edit: Can y’all please stop downvoting this person for being confused? Rule number one. Be kind. They’re not being a dick here or being cruel or anything. Give them the benefit of the doubt please.
JK Rowling is the author of Harry Potter and was primarily known for this. Loved, even, for this. An enormous fanbase. Not to say that there weren’t issues with her portrayal of POC characters or doses of antisemitic behavior (The Goblin Bank literally has a MASSIVE Star of David in the middle of their lobby) but people still loved her nonetheless.
Yet overtime she started adding random stupid things to canon. People asking about bathrooms and her randomly tweeting in response that wizards used to just shit themselves and then magic it all away. This happened more and more with all manner of subjects that started to really point out she was a piece of shit. When people started talking about her portrayal of various different characters, she sort of went off the deep end. She started getting really entrenched in her position and bitter towards everyone. One of these positions was that trans homies are not homies. The typical “mental illness/grooming/rapists” reasoning. Her position within the fandom fell into utter freefall and fractured an enormous amount of said fandom. This then bled into popular culture as a whole because she’s such a popular and influential public figure. She just kept digging and digging and digging and now she’s primarily known online as “That bigoted bitch who wrote the wizard books”. The entire Harry Potter franchise has become slightly toxic to the touch. Hogwarts Legacy was released to immense backlash and almost none of it was the fact that the game was a raging, repetitive and extremely badly written pile of hot garbage that had no character development or story consequences. Even the actor who played Hermione (not sure about others) came out and said that they would have nothing to do with a Harry Potter continuation or reboot if JK Rowling was involved in any way whatsoever which is what led JK and WB to team up to remake the Harry Potter series. There has been a TV show that was announced with JK herself being heavily involved.
While still a massive franchise and a massive fandom, Harry Potter has aggressively slouched in those ratings and has been inextricably linked to the personal opinions of the author formerly known as JK Rowling. Honestly I just refer to her as “that transphobic bitch who wrote about the wizards” most of the time now.