Traditionally, the adjective form and demonym of the city of Waterdeep has been "Waterdhavian". It's spelled that way across many D&D 5E books, including the Sword Coast Adventurer's Guide, many hardcover adventures, and novels like Death Masks.
However, in the lastest Waterdeep published adventures (Dragon Heist and Dungeon of the Mad Mage), it's spelled "Waterdavian" throughout, without the "h". I'm assuming that it's not just some error in editing, since it's consistent throughout these newer books.
Is this an "official" change in spelling that I should be adopting? In particular, the current Forgotten Realms style guide that I can find still uses the "h", and I don't know if there's an update to it available somewhere. Also, does it represent some in-universe revision to how the word is spelled (in the "Common" language I suppose)?