Bebop's ult has two AOEs: around Bebop during the ult and around wherever the beam hits the ground. The beam AOE does more damage than the player AOE.
If an enemy player is in both AOEs at the same time: e.g. they are standing up-close to Bebop and Bebop is aiming the ult at the enemy player...
This just happened to me, too. Just bumping to note that this bug is still present in the latest patch. Looks like this has happened to a handful of other folks in other threads.