https://wccftech.com/wow-shadowlands-level-squish-something-cool/

When the World of Warcraft: Shadowlands expansion launches next year, it’s going to implement a “level squish,” reducing the max level you can attain from 120 to 60. In a new interview with Kotaku, Blizzard provided a bit more detail about how the level squish will work and why they think the new system will be better for players.

Basically, if you’re a new player, Shadowlands will be introducing a new starter introductory area where you can level up to 10, at which point, you’ll be directed toward Battle for Azeroth where you can level to 50, and finally, you can tackle Shadowlands, where you can level to the new max of 60. If you’re a veteran and already own multiple expansions, you can choose which one you want to level to 50 in. Previously, folks trying  to pump a new character up to max level had to wind their way through a number of the game’s sometimes-dated expansions, so this is a major simplification.