This is what Radcliffe wrote. The article links to an article which links the text instead of including it directly. You might also not agree with their privacy statement.

Transgender women are women. Any statement to the contrary erases the identity and dignity of transgender people and goes against all advice given by professional health care associations who have far more expertise on this subject matter than either Jo or I. According to The Trevor Project, 78% of transgender and nonbinary youth reported being the subject of discrimination due to their gender identity. It’s clear that we need to do more to support transgender and nonbinary people, not invalidate their identities, and not cause further harm.

To all the people who now feel that their experience of the books has been tarnished or diminished, I am deeply sorry for the pain these comments have caused you. I really hope that you don’t entirely lose what was valuable in these stories to you. If these books taught you that love is the strongest force in the universe, capable of overcoming anything; if they taught you that strength is found in diversity, and that dogmatic ideas of pureness lead to the oppression of vulnerable groups; if you believe that a particular character is trans, nonbinary, or gender fluid, or that they are gay or bisexual; if you found anything in these stories that resonated with you and helped you at any time in your life — then that is between you and the book that you read, and it is sacred. And in my opinion nobody can touch that. It means to you what it means to you and I hope that these comments will not taint that too much.

Love always, Dan