“She tried to save them — but fate tore them apart” — In her final days, Princess Diana reportedly left William and Harry a desperate warning about power, pride, and the Crown’s curse

I worked for Princess Diana and Prince Harry got a huge warning' -  Celebrity News - Entertainment - Daily Express US

According to Patrick Jephson, a private secretary and confidant of the late princess, her sons would be wise to heed her example.

Princess Diana always looked after the wellbeing of her sons, Prince William and Prince Harry, proving herself to possess a certain motherly touch. Although William was heir to the Windsor dynasty from birth, Diana was opposed to any form of preferential treatment or comparison between her two sons. William and Harry have long said they were the recipients of their mother’s support and wise counsel. In fact, she left them some advice just before her death from a car accident on August 31, 1997.
Diana's warning about royal life to William and Harry revealed | Royal |  News | Express.co.uk
Patrick Jephson, Princess Diana’s former private secretary, spoke of the perennial influence of the late princess on her sons’ life choices. “If they study Princess Diana’s life carefully—and I hope they often do — William, Harry and their advisers will know that she left them many good examples to follow and also a few important warnings to heed. Public affection and the rich rewards of royalty must be earned with self-sacrifice and service,” he told People.
“I’m sure they are grateful that every day she can still guide, comfort and inspire them along the difficult path they were born to follow,” added the royal equerry.
Princess Diana gave Prince William and Prince Harry both 'good examples to  follow' and 'important warnings' about royal life, expert claims | TatlerToday, almost thirty years after the death of their mother, Prince William and Prince Harry are at the heart of a family crisis. Two clans are emerging: the elder son’s clan, surrounded by his father, King Charles III, and the Windsors, and the younger son’s clan with his wife, Meghan Markle, both of whom have become the great pariahs of the palace. Despite speculation about possible reconciliations, the situation remains unpleasant and far from the image Princess Diana had for her sons’ future.
However, despite their apparent disagreement, Princess Diana remained the point of union between the two brothers. As did the princess’s philanthropic convictions—a legacy that is now at the heart of the humanitarian work of Prince William and Prince Harry, both of whom have taken up their mother’s causes. While the elder fights homelessness, the younger highlights the dangers of abandoned minefields.