Please disable Kayn

Not a bug.

Shadow Step

Active: Kayn gains 40% bonus movement speed, is Ghost ghosted and can ignore terrain collision for 1.5 seconds. Immobilizing effects will interrupt Shadow Step.

Kayn heals himself upon moving through terrain for the first time and, if he's not in combat with enemy champions, Shadow Step's duration is increased.

Kayn barely heals when he goes inside a wall....

He really isn't even that strong tho and he can do that once every likel what 15ish seconds. Not that big of a deal