The rift between Prince William and Prince Harry isn’t getting any better. Now money — a bequest from the Queen Mother, who died in 2002 — has become a new source of tension.

When Harry turns 40 on September 15, he’s due to receive nearly $9 million from his great-grandmother, which is more than his big brother received on his 40th birthday two years ago. “Somehow the idea of Harry walking away with so much money seems wrong to William,” an insider exclusively tells In Touch. “In William’s opinion, Harry’s done nothing to deserve it and he’s caused nothing but trouble and heartbreak for the royal family since he moved to America.”

Not that William, who earned $30 million last year, is strapped for cash. But ever since Harry and his wife, Meghan Markle, decamped for California, where they live with their two young children, he has felt repeatedly betrayed as the royal “spare” criticized the monarchy and William in particular. The insider says, “William carries a grudge for every slight and insult.”