Here's another theory I just read on the trashy NYPost, the choice of name is very "rude" to the Queen according to a royal biographer because it was a nickname bestowed on The Queen by her late husband (Harry's grandfather) and to name their child that is demeaning to both of them. At least according to Angela Levin on
Good Morning Britain. Even though the nickname went way back to when she was a child and too young to pronounce Elizabeth correctly and thus became a nickname that both her parents and grandparents adopted. Since Harry and Megan are either awful or scheming people (but are apparently bad at it), maybe they meant to diss the Queen after all.
I put "royal biographers" who participate in shows like
Good Morning Britain and the like and who get quoted in the NYPost on the same level as people who get paid to write listicles and bad takes on Buzzfeed or who spend all their time making awards predictions for film/tv in that I can't believe someone can make a real living by doing of that.