A "stat squish" and "item squish" was implemented to lower the numbers used in the game, e.g. a legendary item previously with a level of 1000 reduced to 265. Unique class-specific buffs are added back, i.e. mages' Arcane Brilliance and priests' Mark of Fortitude. Titanforging—a random event that raises the initial item level of an item gained via drops or rewards—is still in the game; however, if the item is one of those affected by the Heart of Azeroth, then that item cannot be titanforged.
That’s because armor of higher level has higher Azerite power requirements than lower level armor. That means a shiny new piece of Epic gear will have better stats but, unless you’ve been diligent about your Azerite power grind, won’t have as many traits unlocked. You lose options as you earn better gear. Eventually, you’ll grind out enough Azerite to earn those traits back, but you’re left with limited customization until then.
If you need the abridged version, because you’d rather spend an hour in a game than hearing someone talk about a game, you can also check out the excellent “New & Returning Player Guides” series from YouTuber (and World of Warcraft expert) Bellular. And you probably even skip the bits about ”how to purchase” or “how to install” the game, saving you even more time for new World of Warcraft adventures:
I do not recommend going for TBC, although I remember Hellfire peninsula to be decent, everything else is rather slow. Instead go for WotLK, Borean Thundra gets you levelled very fast, and then you can head straight for Icecrown at 67, which is also insanely fast, although admittedly has a few elite quests. You can go to Sholazar Basin alternatively. 2 zones should get you 60-80 no problem.
Level 120 comes and goes. Island Expeditions have unlocked, but it turns out they’re not much fun, and the most rewarding versions are only accessible to premade groups. You turn to Warfronts only to realize they’re not available this week. Fine. You can always grind out better gear. Except as you do, you notice your new gear has higher Azerite requirements than your old gear, which means your shiny new items have fewer unlocked traits than what they replaced. Discouraged, you decide to roll as one of the cool new Allied Races. Except you can’t because they’re all locked behind reputation grinds.
Meanwhile, in Zandalar, the Horde seeks to earn the trust of King Rastakhan so they can use his legendary Golden Fleet against the Alliance. To this end, they assist Rastakhan and his court in dealing with local threats in Zuldazar, fight maniacal Blood Trolls in Nazmir, and face off with serpentine Old God cultists in Vol'dun. Throughout their journey, the Horde gradually learns about an eldricth being known as G'huun, an artificial Old God accidentally created by the Titans and the patron deity of the Blood Trolls. The Blood Trolls and the Faithless Sethekk seek to free G'huun from his prison of Uldir so they can use him to rule Azeroth, and to this end they resurrect G'huun's champion, the C'thrax Mythrax, to destroy Uldir's seal. Rastakhan's own chief adviser, the prophet Zul, is revealed to be the Blood Trolls' secret leader and launches an armed revolt against Rastakhan. With the Horde champions' help, Rastakhan is able to defeat Zul and his forces, but not before Mythrax destroys Uldir's seal.