Prince William turned 37 last week in a day sure to have been filled with fun with Kate, George, Charlotte and Louis.
But there was one noticeable 'snub', according to a Royal insider.
Harry and commented on a Kensington Palace snap of the Duke of Cambridge to mark the occasion.
However they previously shared a picture of the Queen and Prince Philip, leading to claims the that the Sussexes were "pretty rude".
The Mirror reports that Ingrid Seward, the editor in chief at Majesty Magazine thought they could have done more to celebrate the day.
She told Sun Online : "I think it’s a snub if they don’t leave one for Prince William as they did for the Duke and for the Queen.
"If they don’t I think it’s pretty rude and will certainly be construed as purposeful.
"That is the trouble with Instagram it becomes your slave.
"But it's not as if it’s a cousin or a friend – it's Harry’s big brother."
However many fans don't believe there's anything wrong with Harry and Meghan's comment, pointing out that they did the same thing for Princess Charlotte and Prince Louis's birthdays.
However the message for William was much more formal than the ones they sent to their niece and nephew.
Previous comments had featured warm messages such as "lots of love" and contained kisses and emojis, but this one noticeably did not.
The birthday message came the day after Meghan and Harry revealed they were splitting from the Royal Foundation , the Fab Four's charity.
Kate and William will continue the original charity while the Sussexes set up their own, new foundation.
The charity split statement says both couples are "incredibly proud of what they have achieved together" but claims the new structure will "best support Their Royal Highnesses with future charitable activity".
However many fans were worried this is another sign of a growing rift between the two royal couples.
The charity split is the latest way the two couples are cutting their ties to each other.
Last year Meghan and Harry split from the Kensington Palace household, setting up their own office within Buckingham Palace.
Before Archie was born, the couple moved out of their palace home, which was just a few doors up from Kate, William, George, Charlotte and Louis, and set up their new life in Windsor at Frogmore Cottage.
