Kate shared an old picture with her mother, Carole Middleton, on the occasion of Mother's Day in the UK on Sunday.
German news editor Laura Schäfer said Kate Middleton "reacted wrongly" several times in the wake of the interview.
The baby has been named Grace Elizabeth Jane Matthews, her middle names a nod to her grandmothers, Carole Elizabeth Middleton and Jane Matthews.
Kate would have tried to help her sister-in-law "more than she did" if she was aware of the "depths of Meghan's despair" and "wishes she knew more."
Royal Household staff and Royal Communications are reportedly ignoring calls from journalists.
Many gushed over Oprah's interviewing skills and dubbed her "the greatest interviewer of all time."
Harry says that he had three conversations with the Queen about his and Meghan's exit, and they continue to share a good relationship.
The Duchess recalled her first meeting with the Queen, and also said that her sister-in-law Kate is a "good person."
The Sussexes also believed that the "men in grey suits" were obsessed with destroying them.
The brothers both sent legal letters to the British press asking them to keep details about Meghan Markle and Kate Middleton's life private.
The interview titled "Oprah With Meghan and Harry" will be aired on CBS Network on March 7.
The revelation is completely contradictory to the previous reports about the relations between the two royals.
Their rift could be healed as long as Harry and Meghan don't make any personal attacks in their upcoming tell-all interview with Oprah Winfrey.
The revelation comes after Westminster Abbey announced that it will not be hosting the annual Commonwealth Service on March 8.
The transition period has been completed and Prince Harry and his wife have officially resigned from their roles as senior royals.
While Harry and Meghan might stop at two children, William and Kate are already planning their fourth.
Harry and Meghan's second child will be the tenth or eleventh great-grandchild of the Queen and the Duke of Edinburgh.
One continuous theme throughout the entire discussion was that only British designers were chosen to design the royal wedding gowns.
A source claims that Kate knows that her "clock is ticking" and therefore has started trying for the fourth child.
Harry served in the British Army for a decade until his resignation in June 2015.
Carole, who has been isolating in Berkshire with her husband, quipped about the pressure on him to mark her special day.
Prince Harry is currently planning to fly to the UK to see his grandmother Queen Elizabeth II and the rest of the British royal family.