It's a microcosm for science denial or misunderstanding of all kinds. Vegan cats and antivax may not seem related but the underlying misinformation is not dissimilar.

I tried following up on the vegan cat research being posted and it was very difficult to get a solid answer. There are multiple brands of vegan cat food marketed and sold, and it isn't outrageous to believe that our industrial society could find an ethical way to source the necessary nutrients and enrich the cat food.

But also there's very few studies that test the claims of the vegan cat food. What few meta-analysis exist, and anecdotes online, would suggest that all those foods lack certain critical nutrients for long-term feline health. But the anecdotes are drowned out by well-intentioned people who want to believe it works, and the studies are small, rare, hard to read, and locked behind paywalls.