It’s why I put it in a separate comment. It’s been scientifically shown that people often feel threatened and angry at the mere presence of vegans. What it comes down to is that most people want to believe that they’re at least mostly pretty good, but veganism challenges those narratives and highlights that the vast majority of people are very much doing things every day that are very wrong, and that they’re not living by their own standards.
I’ve only been vegan for two years, and have been learning very quickly that I need thick skin for it, and that it means every statement I make on the topic will get scrutinized by the highest standards of skepticism while every carnist can just chime in with all the same tired lies about veganism that have already been thoroughly debunked for years now.