This is what a lot of people don't seem to realise about Rowling. It's not just mean comments on Twitter. It's not even just donations to regressive political parties. She *actively bankrolls* the entire transphobic lobby in the UK. Laws have been changed by her. She is monstrous.
If you need to give people a reason not to support Harry Potter anymore, JK Rowling is actively stripping queer spaces away from vulnerable students who need them. All of the money from her books goes to this.