Hooray! Finally, somebody who acknowledges that Charles could have issued new LPs.

Quoted from the very end of the article:

It was previously reported in 2021 that Charles, in a bid to limit the number of key royals, intended, when he became monarch, to prevent Archie becoming a prince.

To do so, he would have to issue a Letters Patent amending Archie's right to be a prince and Lili's right to be a princess.