"It's tacky, it's royals for hire, royals for rent,” Andrew began, before drawing comparisons to another member of the royal family who was criticised for trying to “flog” goods on TV.
"I remember Prince Michael of Kent in America many years ago was flogging bits of royal memorabilia on American TV programmes, it was stopped within days by the Queen.
"She won't stop Meghan Markle from doing this because they're a law unto themselves,” he added, before saying the endorsements could end up being the Sussexes’ undoing.
"I think as that review continues into how well they're behaving as royals, that review will be published in March by Buckingham Palace,” he said.
The commentator went on to suggest that Harry and Meghan’s commercial activity will likely “speed up calls” for the couple to be stripped of their HRH titles.
"HRH's should not be flogging coffee even if it is environmentally-friendly and getting it promoted on a chat show," he said.
The backlash comes after Meghan’s pal Oprah Winfrey seemingly spruiked the non-dairy products on her Instagram feed on Tuesday.
Taking to the social platform, Oprah shared a video of a gift basket with plenty of variations of the products made by Clevr Blends, a female-led company that creates instant oat milk lattes.
"On the first day of Christmas my neighbour 'M' sent to me...a basket of deliciousness!" Oprah captioned a video of herself spruiking the milk, before adding, "yes that M," alongside a crown emoji.
She concluded: "My new drink of choice for the morning and night. Wish I had @clevrblends sooner cause I would've added it to my Favorite Things list. #HappyHolidays."