Prince William is reportedly unhappy with Prince Harry's $8.5M inheritance payday on his 40th birthday, according to an expert.

It appears that not everyone is happy about Prince Harry receiving an estimated $8.5 million on his birthday.

The Mirror in the U.K. reported that the Duke of Sussex, who is turning 40 on Sunday, will receive a significant inheritance from his late great-grandmother's estate, which is more than what Prince William received when he turned 40 due to the Prince of Wales being the heir to the British throne.

The Queen Mother died in 2002 at the age of 101.

Helena Chard, a British broadcaster and photographer, stated to Planet Chronicle Digital that William, 42, may become "disgruntled" due to his younger brother's tell-alls that have shaken the monarchy, and the substantial inheritance he is expected to receive.

"Harry has been unsupportive, scathing, and hurtful towards the royal family, according to Chard. On the other hand, Prince Harry will be thrilled to have won the top prize because he has always felt inadequate compared to Prince William."

Prince Harry's financial comfort will ease King Charles' relief that he won't need to write any more memoirs attacking the royal family, according to Chard.

"It is unlikely that King Charles will engage in conversation with his son Prince Harry because of Harry's ongoing conflict with the U.K. government over taxpayer-funded security. Harry is seeking his father's assistance in obtaining the security measures he desires."

According to Christopher Andersen, author of "The King," the Queen Mother had previously disclosed to Planet Chronicle Digital that she had placed two-thirds of her estimated $120 million fortune into a trust fund for her great-grandchildren.

An expert believes that Prince Harry and Prince William need an intervention to end their feud.

"When Prince William became Prince of Wales, he would inherit the Duchy of Cornwall, which now has assets worth over $1 billion, as shared. Meanwhile, the value of the trust has increased, including Harry's share."

Hilary Fordwich, a royal expert, revealed to Planet Chronicle Digital that William is displeased with Harry's birthday payment.

"According to Fordwich, Prince William is unhappy that Prince Harry will inherit $8.5 million from the Queen Mother's estate. Although he doesn't resent the money itself, he believes the Queen Mother couldn't have anticipated the actions of Prince Harry on the family."

Fordwich stated that he despised Wallis Simpson for the harm she caused to the royal family and the monarchy through the abdication crisis, which was triggered by the American divorcée's influence on Queen Elizabeth II's uncle, Edward, Duke of Windsor.

After Edward relinquished his role as monarch, George VI was appointed king. Subsequently, Elizabeth, who was previously Princess, became the heir to the throne.

Edward and Wallis, having been disconnected from the royal family, faced financial difficulties. As a means of earning money, they both penned memoirs.

Fordwich noted that not everyone shares William's perspective.

She claimed that such a lump sum might help offset the need for Prince Harry and Meghan Markle to sell more royal stories.

The inheritance will provide the Duke and Duchess of Sussex with a "breather" as they navigate their life in America, according to Chard.

"Prince Harry will be thrilled to receive his inheritance on his 40th birthday, said Chard. The royal family and the public hope that the Sussexes will move on without causing any more harm and upset."

King Charles and Prince William are currently focusing on what they believe are important, with renewed vigor, according to her.

"[Prince William feels] Harry has been unsupportive, scathing and hurtful towards the royal family." — Helena Chard, British broadcaster and photographer

Ian Pelham Turner, a royal expert, believes the king, 75, should initiate peace talks with Harry, as reports suggest the monarch has stopped answering his son's phone calls.

"In my view, this milestone should motivate King Charles to take action instead of remaining stagnant and fulfilling the expectations of Britain as its monarch. Currently, it is a disgrace that the values that Harry and Meghan can bring to Britain are not being utilized effectively. The inheritance serves as a tragic reminder that his great-grandmother, who saw the potential in him, passed away before he could fully realize it."

According to Andersen, the reason trust doesn't develop until age 40 can be explained by a specific factor.

Andersen stated that for a woman who almost reached 102 years old, 40 must have seemed like the ideal age to receive some extra money - young enough to enjoy it but also old enough, and hopefully wise enough, not to squander it.

"It's likely that the princes' great-granny would have disowned Harry entirely if she had known about the trouble he caused the family."

In 2020, the U.K. Times reported that the Queen Mother bequeathed a portion of her wealth to Harry, who received it through a trust fund intended for her grandchildren.

In 2002, Queen Elizabeth II avoided paying an inheritance tax of nearly £20 million on her mother's legacy, which increased the value of her grandchildren's fortune.

Princess Diana's estate, worth £21 million ($27 million), was inherited by William and Harry, who each paid £8.4 million ($10 million) in inheritance taxes.

Any future commercial earnings of Harry will be subject to tax, the outlet stated.

The Duchy of Cornwall released its Integrated Annual Report for the 2023-2024 financial year, marking William's first full year as the Duke of Cornwall.

When Charles became king, William inherited the estate and title as the heir to the British throne.

The Duchy of Cornwall estate yielded William over $30 million in his first year's income.

William, as a member of the royal family, does not receive a typical income, according to People magazine. Instead, his annual expenses are mostly covered by the Duchy of Cornwall, which was founded by King Edward III in 1337 to provide funds for the heir.

The estate, valued at over $1 billion, covers 130,000 acres across 23 counties in England and Wales. The estate comprises land, farms, houses, and other assets to support the heir and their family. It is reported that William pays income tax on the entire income he receives after deducting household expenses, which have not been specified.

Harry's 2023 memoir "Spare" alleges that he and his wife were portrayed as villains by the British media, while William and Kate Middleton were viewed as virtuous. Additionally, Harry accused palace officials of deceiving him to safeguard his older brother.

The reasons for the Sussexes' decision to quit royal duties and move to the U.S. in 2020 were the media's racist treatment of Meghan, who is biracial, and a lack of support from the palace.

In an interview with Oprah Winfrey in 2021, the couple claimed that the royal family was unconcerned about Meghan's mental health struggles. Harry stated that his relationship with William was currently strained.

Harry resides in California with his 43-year-old spouse and their two young offspring.

The Associated Press contributed to this report.