The one he took offense to was the one that was taking during the Christmas season in 2019 where George was mixing a pudding while William, Charles and The Queen looked on, and then a separate posed photo.
https://www.abc.net.au/news/2019-12...s-pudding-with-queen-william-charles/11821898
https://www.tmz.com/2020/01/03/roya...elizabeth-prince-charles-duke-william-george/
I think that it is interesting because Harry has indicated that he understood that he has a shelf life and felt pressure to make his mark before his expiration date,* this was reported in Valentine Low's book but it was also reported even before then and IIRC that was before Meghan.
Dare I say that I get his conundrum. I think that some royals are fine with being background and supporting players. But there are non-heir apparent royals who get a lot of attention due to their proximity to the monarch, along with other factors like youth, glamour and charisma, and are used by the institution because of the interest in them and then expected to graciously step aside when the interest in them diminishes. The royals that I think that this applied to, in addition to Harry prospectively, are Margaret, Anne and Andrew. Both Margaret and Andrew had struggles in their later years and it is not difficult for me to believe their struggles were in part due to their diminished status.
Anne is an exemplary royal and has been for years, but I won't rule out even Princess Anne struggling with her status changing.
Yes it is ridiculous for Harry to resent a 4 generations photo shoot, and while it is the ultimate champagne problem and I really disagree with actions and attitudes that Harry has displayed, I get that a royal would struggle with being a top tier royal, who has made a significant contribution to the institution's standing, to having his status diminish.
* IIRC he considered that his time would be up when George became an adult.