"It's in Germany so it's probably not going to make a big storm over in the U.S.," he added. "But it's still a major blow for a couple who have seen their popularity plummet like a stone falling in a well since they left the U.K."
OK! previously reported the unscripted program could impact the couple's public image.
"Until the film comes out, everything is speculation," PR expert Ryan McCormick told an outlet when chatting about The Lost Prince. "However, I think that if the special does not get a healthy amount of viewers, it would be a foretelling sign that Harry and Meghan's popularity has truly waned."
"If the documentary reveals fresh scandals and portrays the duo as opportunists seeking to return to the well of royal family secrets (which once propelled them to peak public interest), it will be a calamity for any reconciliation with Buckingham Palace," McCormick added. "It will also hurt their reputation and likability."