https://i.imgur.com/2Ivnm1A.jpg
https://i.imgur.com/AegnyUF.jpg
It is the bottom half of the tree in New Dalaran. Very annoying, distracting and possibly seizure inducing if you get close enough for it to fill up the frame. It won’t stop flickering unless you get near and manage to land the correct camera angle. Luckily there is no issue with the similar but bigger holiday spheres in Orgrimmar and Ironforge.
Also this is what rotating the camera inside of the Orgrimmar Barber Shop does to the game.
https://i.imgur.com/5CkpAZ5.jpeg
https://i.imgur.com/Zq1ZdXp.jpeg
https://i.imgur.com/lHHg7Rw.jpg