The real problem here is not manipulated images, as I am sure that the British royal family, like other royals and celebrities, have long had official photos manipulated. From in camera techniques like lights and reflectors to retouching negatives to remove blemishes, and unsing composites of multiple photos....and latterly Photoshop.
The problem in this instance was the plethora of conspiracy theories about Kate which were doing the rounds on social media. The customary lack of detailed info about her "abdominal surgery" fuelled people's desire to fill in the blanks with tinfoil hat stuff....including but not limited to "she's dead".
Then came the image, which was supposed to present a happy, well looking, recovering Kate with her children. But the photoshopping was actually quite obvious, and while there's a perfectly reasonable explanation.....the conspiracy nuts continued with their social media posts about her being dead, or a lizard-being, or bed-bound and so on.
The announcement that cancer was discovered as a result of the surgery and that she's receiving ongoing treatment for that ought to have nipped all the conspiracies in the bud. But now they have shifted to "Kate's cancer was caused by a mRNA turbocancer injection". Honestly, she has announced all anyone outside the family needs to know....let her recover in relative privacy.
I don't *like* manipulated images but I am equally sure that pretty much all people in the public eye do it for official portraits. They wear makeup and have hair stylists too.
BTW Paul McCartney is also not dead.