https://www.polygon.com/2018/7/27/17623158/blizzard-leveling-problems-xp-world-of-warcraft-patch

World of Warcraft patch 7.3.5 introduced a slightly slower, more interesting leveling experience through the old world. But since Blizzard introduced patch 8.0 two weeks ago, players have been struggling to level through the old content effectively.

With 8.0, Blizzard introduced World of Warcraft’s second ever stat squish — where all the numbers in the game are lowered across the board for clarity. While it may make the game easier to read, it has caused some serious in-game problems. Since the patch, Blizzard has been throwing out hotfixes each day, fixing things that the stat squish either forgot to alter or simply broke.