Valve changed the look of the header, settings screen, server browser, and other elements to appear more similar to the new UI for Big Picture mode and the Steam Deck.

Really good news for serious World of Warcraft players. It looks like Blizzard, starting with Wrath of the Lich King will store all your customized UI odds and ends—dungeon maps, coordinates ...

It's something the game's default UI has been sorely missing for quite some time, resulting in players turning to free third-party add-ons to meet their needs, specifically an add-on called WeakAuras.