Mirror image? I think people are reading too much into this portrait.
....."Mr. Yeo said his goal was to produce a more modern royal portrait, reflecting Charles’s desire to be a more modern monarch, reducing the number of working royals and scaling back the pageantry of the coronation (all things being relative).
Still, the choice of shade seems particularly fraught given the … well, firestorm the king has endured since his ascension to the throne.
Consider, for example, the continued falling out with his second son, Prince Harry, and the publication of Harry’s memoir, with its allegations of royal racism; the related calls for an end to the monarchy; Charles’s cancer diagnosis; and the furor over the mystery about Catherine, Princess of Wales, whose own cancer diagnosis was revealed only after increasingly unhinged speculation about her disappearance from public life...............
https://www.nytimes.com/2024/05/15/style/king-charles-iii-portrait-jonathan-yeo-red.html