Blizzard is nerfing one of the most unorthodox leveling methods in patch 12.1: Earthen Skyriding.
To those unaware, this leveling method involves taking advantage of the Earthen racial ability 
Wide-Eyed Wonder, and consists of leveling exclusively by Skyriding around the world. With this method, you can level a fresh character from 10 to 90 in less than 3 hours by following the best routes. (source)
You can see an example below.
Buffs to Compensate for the Nerf
To compensate enraged Earthen enjoyers, Blizzard is buffing another Earthen racial: 
Ingest Minerals. The buff will increase effectiveness from the “food” buff received by the racial by 30%.
While a welcome change for those doing max-level content, for those just looking to level more alts, this change is irrelevant.
Only a Few Weeks Left to Level Earthen
Note that this change will only take place with Patch 12.1. This means you still have about 6 weeks or more to level Earthen characters using this method if you want.
Blue Post
Midnight: Curse of Ula’tek PTR Development Notes
CHARACTERS
- EARTHEN
- Developers’ note: In Curse of Ula’tek, we are revisiting the amount of XP gained when exploring zones. This will particularly impact the leveling speed for Earthen characters, who receive significantly more exploration experience via their Wide-Eyed Wonder racial ability. To compensate for the decrease in experience gains from exploring zones, we are increasing the benefits of Ingest Minerals for Earthen.
- Baseline experience gained from exploring zones reduced by 60%.
- Experience gained from exploring low-level zones is no longer reduced from baseline.
- Effectiveness of Well Fed gained from Ingest Minerals increased by 30%.
