With Quinn's rework, her ultimate changed from "transforming" her into Valor to a special visual channel which renders her unable to attack (and is interrupted by damage).
Unlike her old ultimate, when changing her form, Quinn doesn't change to a melee champion or loses attack range anymore. The strongest indicator though possibly is Quinn's inability to buy Titanic/Ravenous Hydra, unlike regular Shapeshifters.
As with her rework, I claim that Quinn does not qualify as Shapeshifter anymore, and as such she should be removed from the Shapeshifter category (which I can't do). But as Quinn's ult still is a major gameplay factor in her kit and the term Shapeshifter isn't precisely coined, I think it is in order to first discuss whether or not her removal from the shapeshifter category is in order or not.
Shapeshifter is a meaningless term if it's only a visual effect if you ask me. However, the term isn't coined, and depending on the like or dislike of the wiki, I wanted to know whether it's supposed to be a visual effect or a gameplay element.