[GAMEPLAY] Duskblade of Draktharr Passive - Blackout bug

As the item description says, the Passive - Blackout of Duskblade of Draktharr should be activated when spotted by an enemy ward. Then while it is active it disables all nearby ennemy wards and traps.

But I just played a game as Teemo and when enemy with Duskblade of Draktharr would go near my shrooms, it would activate the Passive - Blackout and disable all my shrooms nearby while there were no wards at all.

If I recall correctly shrooms are considered as traps and not wards, am I wrong?