Bug with the damage multiplication on Zoe's E

I recently played a game against a Zoe, when they would hit a q after being slept by the e I noticed that it appears to do double the q damage as true damage. I looked at the tool tip and the tool tip appears to say that there is a cap to this bonus damage specifically,

"Attacks and spell hits break sleep but deal double damage, **up to **60/100/140/180/220 (+40% Ability Power) bonus true damage."

I am not sure if this is the intended function of the ability and the tool tip is just incorrectly worded, or if the damage is currently bugged.