Their biology is still that of a carnivore.

"The cat (Felis catus), also referred to as domestic cat or house cat, is a small domesticated carnivorous mammal." https://en.wikipedia.org/wiki/Cat

"A carnivore, or meat-eater (... Removed for brevity...), is an animal or plant whose nutrition and energy requirements are met by consumption of animal tissues (mainly muscle, fat and other soft tissues) as food, whether through predation or scavenging." https://en.wikipedia.org/wiki/Carnivore

Further down on that same article, under characteristics:

"Characteristics commonly associated with carnivores include strength, speed, and keen senses for hunting, as well as teeth and claws for capturing and tearing prey."

"Carnivores have comparatively short digestive systems, as they are not required to break down the tough cellulose found in plants."

"Many hunting animals have evolved eyes facing forward, enabling depth perception. This is almost universal among mammalian predators"

Scientifically, according to their biological makeup, and nutritional requirements, cats meet all the criteria for predatory carnivores.

This is their biology. I'm not arguing for or against any science that makes them no longer required to eat actual prey/flesh that they needed to hunt and kill themselves. Biologically, their characteristics, digestion, and by proxy, their nutritional requirements, very solidly put them into the scientific category of carnivores.

One of the chief biological indicators of a carnivore vs an herbivore is digestion. Whether the animals digestive tract is designed to break down the cellular walls of plant matter. Cats lack the biological capability to break down the cellular walls in plants because of how their digestive system is configured.

Among everything else that points to them being a carnivore, that's a big one....

Just because they can get the nutrition they need from not being a carnivore doesn't change their scientific classification as a carnivore. They've evolved into efficient hunters, and though, for domestic cats, they are not required to hunt to live, they have all the tools for it.

Until they evolve to be capable of digesting plant matter more efficiently, that classification will remain unchanged. Regardless of whatever pseudo-science you want to convince yourself of.