Overwatch players have discovered that Moira is able to send her orbs completely through walls on the Blizzard World map.
Moira's ability to send out healing or damage orbs is one of the most powerful tools in her kit, but the orbs are supposed to bounce off of walls or any other surface they come into contact with.
This allows Moira to send orbs out to damage the enemy team or heal allies and gives players the ability to somewhat plan out where the projectiles will go, most of the time, that is.
In the gif, posted to Reddit by user LonelyAtTop, Moira shoots her orbs at the base of a wall near the first chokepoint, and the orbs fly right on through like there's nothing there. They even manage to recreate the bug multiple times on different areas of the map.
The bug seems similar to one discovered by players on Busan, just after the map came out, that also sees Moira's orbs fly through what should be solid walls.
Just like when the Busan bug was noticed, players suggested that this has to do with the way the game engine processes Moira's abilities, along with the way it renders walls and other structures, causing the projectiles to pass through at either the top or bottom of the wall.
Blizzard hasn't come out to address the bugs or provide any solution to the issue, so it looks like phantom orbs are just something players will have to get used to.