"While opting for some mega expensive brands including Givenchy, Chanel and Hermes, Meghan also showcased a more low-key approach to dressing than many have been used to seeing."

My guess is that Top designers don't want her to be seen in their clothes.
https://www.dailymail.co.uk/femail/article-12508173/Meghan-Markle-300k-invivtus-games-wardrobe.html