Zarya's shield reveals invisible Sombra

When Zarya applies her shield to an allied Sombra, the shield is visible to the other team, and Sombra (even though she is invisible) is revealed, and can be shot/killed in the process. Unsure if this is working as intended, or is a bug, but I just killed an invisible Sombra that their own Zarya shielded through this method. Was on Lunar Colony, (me on attack).