Both a previously opened Realm & a newly reset Realm are using a swamp map instead of a desert map. However, the geography of the swamp map does not match up well to the actual terrain.
Before update today I started a Desert Astrolabe realm and saved after completing some of the POIs. After installing the update I reloaded and noticed that the "desert" map was now showing a swamp realm map. I'm unsure how this will affect gamepla...
I started a new character in Offline with a Desert Abeyance realm. When I look at the map, there is ocean around it as if it was a Forest or Swamp realm, but the mountains and POIs seem to be correct. I can walk around in the ocean. :-)
Yes, Normal Herb Desert has a Swamp map. But at least all the POIs are in the right places and the mountains show correctly.
Happens in all Desert realms. Had this happen in a Desert Antiquarian non-ascended.