Prince Harry "blew royal protocol out of the way" when he released a statement in Meghan Markle's defence in 2016.
According to The Sun, Harry released a statement about media harassment directed at his then-girlfriend just days after their relationship came to light.
But the outlet reports that it blew his father Prince Charles' week-long trip to the Middle East "out of the water".
The BBC's new documentary on royal reporting, The Princes and the Press, reveals that journalist Robert Jobson had promised Prince Charles the front page of the Sunday Express about his work in the Middle East.
He told the cameras, "When you're on a trip, say with the Prince of Wales in the Middle East, and all of your negotiations for a week to get the chat with the Prince of Wales, to say, 'We guarantee you the splash,' all goes out the window because Harry releases this big statement about the press and about their treatment of Meghan was outrageous."
It's just one of several revelations in the controversial new documentary, which has already been slammed by the Queen, Prince Charles and Prince William in a rare joint statement.
The royals have lawyers ready to take action against the BBC over the documentary, and are set to complain to UK media regulator Ofcom for the first time.
The first episode aired this week in the UK and explored the Sussexes' relationship with the press.
One royal correspondent claims Prince Harry "stared daggers" at the media during an Australia tour in 2018.
He claimed it happened amid Harry and Meghan's tour of Australia, New Zealand and Fiji.
The Times' royal correspondent Valentine Low said Harry had been "pretty grumpy" throughout the tour and alleged that the prince confronted members of the media aboard a plane back to Sydney from Tonga.
At a welcome ceremony in Fiji, "it was very interesting watching them both, because Meghan was sitting just absolutely perfect on a little throne, Harry was just glowering.
"He was cross with the media, and he spent the entire welcome ceremony just diverting his gaze to one side just to stare daggers at the press pack."
Low went on to claim that Harry was told by his team to speak to the media.
"He came back, and said something to the effect of, 'Thanks very much for coming guys – not that you were invited," he revealed.