The former Vanity Fair editor added: “She had starred in the equivalent of a blockbuster film and wanted her leading-lady status to be reflected in lights.”
Meghan and Harry travelled to Australia, New Zealand, Tonga and Fiji in October 2018 months after their royal wedding.
The trip by the couple was seen as hugely successful.
But Ms Brown said Meghan felt her “star power” was “bigger than what she was allowed to do in the monarchy”.
Speaking to 60 Minutes Australia in May, the royal author said: “That was something that puzzled the royal household tremendously.
“Their tour of Australia was a wild success, more successful than Kate and William’s, in terms of crowds and the adulation.
“There was a real sense of disappointment when she came home that somehow she was a star beyond, you know, anything one had seen before, except for Diana, really, on this tour.
“I guess, it was the star power essentially that she felt now was bigger than what she was allowed to do in the monarchy.”
The Sussexes officially ended royal duties in March 2020 for a new life in the US.
They have set up home in the celebrity enclave of Montecito with their two children Archie and Lilibet.
Their post-royal careers include deals with Netflix and Spotify to make shows and podcasts.
Source: EXPRESS CO UK