I have looked closely and can see a couple of little glitches that have been mentioned - and maybe this is a pic that was taken 4-6 months ago, but I am struggling to care, honestly. I am not having a go at people who are concerned/asking questions, or thinking I'm superior because I'm not faffed, but Kate must be sick of all the 'where is Kate' cries.
Kate and the Royal Family have probably just had enough of the speculation about people going on and on about Kate. Where is she? Has she been kidnapped by aliens, has William eaten her? Are they fashioning a clone? So many questions! 
So they just rattled up a pic on Mothers Day and said it was Kate and the kids this weekend. Maybe it was, maybe it wasn't, but seriously,? Who cares? Maybe Kate has not recovered enough to face the public yet/isn't looking her best (Or feels she doesn't look her best,) and wanted this photo being presented.
Bet she wishes she hadn't bothered now! The speculation and conspiracy theory are bonkers. I think people need to leave the woman alone. She said she would be offline til around Easter, so why all the fuss?