This article offers a fair view on both sides of the divide: https://cats.com/vegan-cat-food
I think the entire article is summed up in its conclusion:
You only have two options. One is to disrespect your cat’s needs and desires by feeding him a diet that’s morally meaningful to you and perhaps other animals, but utterly unnatural to a carnivore. The other is to, if even in an indirect way, kill Peter the Chicken to feed Paul the Cat.
I know there are people who feed their pets a vegan diet because they themselves are vegan. Whatever their reason may be, we are not judging them. The conclusion (in blue) above, sums it all up.
As we’ve said, this isn’t a wonderful world because all living beings have to eat. Some eat plants, some eat plants and meat while some eat meat. All sources of food will endure suffering.
Such is this world.
Cats are carnivores.