It depends on your tolerance for how bad that person is and how much you want to contribute to their financial well being. For JK Rowling, my opinion is that if JK just said she doesn’t like trans people, I’d disagree, but that by itself may not be a reason to not enjoy the work produced by her. However, she actively fights to put down trans people and spreads transphobia. That is reason enough for me to never do anything that will finance her and therefore support her actions.

In this case, Tolkein is long dead. Nothing I do now will contribute to him further pushing and supporting fascism.

Everyone gets to make this choice on their own. Nobody said you’re not allowed to enjoy that art. If you decide that you’re fine supporting artists through thick or thin and there’s no line they can cross that will turn you away, then you can’t be surprised or upset when other people change their opinion of you as a person. If you’re okay with that, then that’s fine, it’s your life, live it.