Princess Diana's former butler called Harry and Meghan 'toxic'.
Former New Zealand PM Jacinda Ardern joined Prince William's project.
Ardern's appointment came after distancing herself from Harry and Meghan.
Prince William welcomed Ardern's addition to the team.
Paul Burrell said Ardern chose William and Kate over Harry and Meghan.
Burrell criticized Harry and Meghan for seeking fame and wealth.
Harry and Meghan got married in 2018 and have two children.
They stepped down as senior working royals in 2020.
They appeared in a Netflix docuseries and Prince Harry released a memoir.
Ardern's commitment to sustainability and experience as PM were praised by Prince William.