The Battle for Azeroth Pathfinder achievement is no longer required for flying in Kul Tiras and Zandalar in Patch 10.1.
Battle for Azeroth is two expansions old with the launch of Dragonflight, so Blizzard removed the Pathfinder requirement in Embers of Neltharion.
The achievement still rewards the Wonderwing 2.0 mount.
Thanks to MrGM for spotting the change.