Reddit user holoroh spotted an island on Dragonscale Expedition maps that hasn’t been added on live servers yet.
The zone is near the crater located in Ohn’ahran Plains. While the live map of the Dragon Isles does not contain it, the island can be found on Dragonscale Expedition maps.
For comparison, here’s the live version of the map, which doesn’t contain the marked island.
Blizzard confirmed a new zone coming in Season 2 (Patch 10.1), so we’re probably dealing with something similar to Mechagon Island.