So I was reading the Kayn changes in the patch notes and noticed something

> Passive - The Darkin Scythe BUGFIX Kayn no longer gains transformation progress from ticks of Corrupting Potion, Deathfire Touch, Red Buff, or Challenging Smite. (Other periodic effects, such as Ignite, already had no impact on transformation progress.)

I mean, I know they wanted to fix this anyways, but is it considered a bugfix? Isn't Kayn supposed to get orbs from dealing damage? Or is it only supposed to be direct damage from Kayn, and not external effects from items and masteries?