So from another reviewer: William comes in for a kicking from Scobie about the Martin Bashir/Diana interview.
Bashir, if you all remember, used false documents suggesting that Diana's royal protection was spying on her, in order to induce her into that interview. When this became public, William demanded the interview never be aired again, said Bashir had contributed to Diana's paranoia, and led her to dismiss her royal protection (the loss of which possibly contributed to her death). He wanted it never to be aired again to protect his mother's memory.
Scobie accuses William of trying to silence Diana and says William is smearing Diana with the paranoia comments - and that William has done the same to Harry. He says William is shutting down the Diana interview to protect the monarchy. He justifies H&M using the Bashir interview in their Netflix series as them being the only ones protecting Diana and honouring her, by giving her a voice.
I don't remember a single time when William has said anything (in public) about Harry's mental health. Harry is the one that talks about his own mental health - and yes, paranoia. How has that landed back on William's lap? How has the Bashir shit show landed back on William's lap? All roads of blame seem to lead to William and Catherine.