It didn't take long for the haters to weigh in with their opinions on the royal couple's comment.
"I know that this is their nephew, but they should treat him with respect. And first of all, he is for them Prince George!" one person wrote.
"This greeting is obv [sic] not written by the usual admin of this account.... so informal especially for a future King," wrote another.
"He is HRH Prince George to you! Don't forget to mention!" another said.
"You can't bring yourself to use his title, huh?" one other wrote.
Thankfully, some fans came to the defence of the royal couple.
"They can't win," one person said defending the Duke and Duchess.
“Some of you really need to get a hobby,” another royal fan said.
Duchess Meghan has found herself under increasing pressure lately, as she has been slammed for everything from holding her baby Archie incorrectly on a day out with her family, to wanting privacy while watching Wimbledon.
The actress officially joined the royal family when she married Prince Harry in May 2018.