There are a few things I would like to point out. And i know some of these things you have pointed out (for example you do say that pet food is made up of by-products that are not suitable for human consumption), but i would like to hear your response to these points.

1. Lack of scientific evidence. This article claims that vegan diets can meet all the nutritional requirements of cats, but this claim is not backed up by strong scientific evidence. While there have been some studies on vegan diets for cats, they are limited in scope and do not provide conclusive evidence that such diets are safe and healthy for cats in the long term.
2. Overstating the environmental impact: This article suggests that feeding cats a vegan diet would significantly reduce the amount of meat consumed, thus reducing the environmental impact of meat production. However, it overlooks the fact that the majority of meat produced for pet food is made up of by-products that are not suitable for human consumption. Therefore, the environmental impact of pet food production is not as significant as this article suggests.
3. Ignoring the natural diet of cats: While it is possible to create nutritionally complete vegan diets for cats, it goes against their natural diet as obligate carnivores. A vegan diet may not provide all the nutrients that cats need, which could lead to health problems in the long term. And i know you have responded to this comment, however you seem to be neglecting the fact that cat's evolved to specifically eat meat. This comes back to the lack of scientific evidence as well, and we do not know the long term impacts of changing their diets. And i would just like to say that herbivores themselves eat small amounts of meat from time to time, and so if herbivores, which evolved to get the absolute most out of plants, need to eat meat sometimes, what will that say about transitioning carnivores to meat?
4. Overlooking animal welfare concerns: This article argues that feeding cats a vegan diet would reduce the number of animals killed for pet food production, but it overlooks the potential negative impact on the welfare of cats. Some cats may not be able to digest a vegan diet properly, leading to digestive issues and other health problems. Which again, leads to the lack of evidence on this topic.
5. Disregarding personal choice: This article suggests that humans should make domestic cats vegan, but it ignores the fact that cat owners may have different beliefs and preferences when it comes to feeding their pets. It is important to respect personal choice and allow cat owners to make informed decisions about what to feed their pets.