Indeed, we don’t know how the Prince is truly feeling. But he is not publicly denouncing the acquaintance(s) of his who has been making strongly-worded (albeit still anonymous) complaints to Tom Sykes, currently royal reporter for the Daily Beast. Mr. Syke’s reports are the source of the stories you read.
This does not necessarily mean the Prince of Wales is sincerely considering stripping the HRH titles when he becomes king. But the Prince does seem to be fine with letting his sister-in-law think he is angered by her breach of the agreement.
The
comments from acquaintances after HRH in the gift card:
The former courtier added: “Charles might be happy to put up with this, but William won’t. He loathes and despises Harry and Meghan with every bone in his body, he believes they have betrayed everything the family stands for and the idea that they are using their royal status as a calling card will enrage him.”
A friend of William’s told the Daily Beast: “Charles has completely lost control. It’s apparent that Harry and Meghan have every intention of making his final years a misery, just as he feared they would. Meghan using her HRH exposes how weak and enfeebled he is. She knows he won’t do anything. There is no way King William will stand for this. The titles will simply be removed when he is king. A way will be found.”
A friend of the king told the Daily Beast that while the king was likely to be aware of the controversy, he would not seek to have the issue raised with the couple.
The king’s office declined to comment. William’s office did not respond to a request for comment.
Their earlier
comments after the YRH in the Ukraine vice presidential letter:
“It’s outrageous. Every time you think they can’t make it worse, they make it worse,” the friend of the king said. “The deal with the HRH was a way to stop them cashing in while letting them walk away with pride and dignity and trust, and now Markle is using her HRH on a website which seems to exist to sell jam.”
“They say they want reconciliation,” the source added. “I’m sure the king’s first reaction will be dismay, but he simply doesn’t allow himself to get angry about things like this anymore.”
A friend of Prince William’s said: “It’s actually quite a clever way of testing the water, because there is deniability there, she can say, ‘Well, I just wanted to publish this nice letter to raise awareness for Ukraine, and oops! they got my name wrong—but oh, actually, now I think of it, I never gave the title up anyway, and maybe I will start using it again.‘"
“It’s a step in the wrong direction, basically, away from the agreement. You’d have to be an idiot to believe that she didn’t know exactly what she was doing when she posted that message, unedited, to her stories.”
An expert in heraldry who knows the family told The Daily Beast: “There were plenty of people at the time who said it was a mistake to make not using the title a mere gentleman’s agreement rather than just removing it. This post may not matter in and of itself, but it raises a bigger question: What are they going to do if she simply starts using her HRH again? She probably can’t be stopped as things stand right now. The bottom line is, she is, officially, an HRH. It was never removed.”
Referring to it as a style is fine as well. 
