In fact, cats fed a proper vegan diet tend to have better health: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10499249/

It actually never definitively says that in any of the studies mentioned... This particular study relies entirely on self reported results, with less than 10% of the sample sizes being fed a vegan diet, with no actual controls in place. It's a meaningless study. It honestly reads like a fluff piece where they collected some surveys from an already pro-vegan community. As we've seen from the rhetoric surrounding this situation some vegans will absolutely feed their pets inadequate food and feel good about themselves while doing it.

And the final nail in the coffin:

This research and its publication open access was funded by food awareness organisation ProVeg International (https://proveg.com).

Ahhh... there it is.