One thing to add that I feel might be being missed here- there’s a big difference to me at least between supporting the art of someone who is problematic only in the sense that they hold problematic views that they largely keep to themselves or have done bad things (as the slippery slope sort of argument that you allude to would apply to), and someone who’s money which comes from their art actively funds hate campaigns such as JK Rowling’s monetary support and lobbying of transphobic causes.
The first is only an abstract moral problem (does someone who isn’t a great person deserve money and royalties as a result of my support of their art). The second is a material contribution to the worsening of trans people’s lives. Which is essentially the role any money directly or from royalties made off harry potter plays, supporting it is directly funding anti-trans campaigns so trying to claim any seperation seems ridiculous to me.