The main reason for the suspicion is due to one defining characteristic about Meghan that sets her apart from the rest of the royal family -- she's American. Many fans have pointed out that, throughout some of the page's recent posts, the American spelling of words are used. While Americans spell words like organization and energized with the letter z, British folk spell those same words with an s.
In a post that highlighted Baby2Baby, a charity that provides children with necessities, the caption spoke about Meghan's Los Angeles roots and referred to the non-profit as a "very special organization."
Another post highlighting the money charities received in honor of Baby Sussex said Little Village HQ's team was "re-energized" as a result of the donations.
In the same post, another reason for the Meghan theory came to light -- the use of an American name of a product. The page once again wrote of Baby2Baby, writing that it was able to disperse "diapers" to over 5,000 children in need, but in the U.K. diapers are referred to as "nappies."
Additionally, the same post referenced both American and British currency, writing, "Whether a $5 donation, £1000 contribution, offering to volunteer, or spreading the word -- you’ve played your part."
Despite the above instances, the @SussexRoyal account does frequently use British spellings and terms, but that hasn't stopped fans from speculating!
This also isn't the first time Meghan and Harry's Instagram account has gained attention. Less than six hours after the royal couple unveiled their new account, it had already amassed 1 million followers, a milestone that Guinness World Records said was reached in record time. About two weeks after its creation, the account now has more than 4.7 million followers.
The Sussexes' recent appearance on social media comes just ahead of the arrival of their first child. ET recently confirmed that the pair moved into their home at Frogmore Cottage and are eager to welcome their little one.
"Harry's attention is completely absorbed with the birth of his first child," a source recently told ET. "He can't wait to become a father. He's been doing everything he can to put Meghan at ease."
As for Meghan, the source said that "she'll be a fantastic mother."
"She is so wonderful with children and they are both so excited," the source added.
Watch the video below for more on Harry and Meghan.