Paging All Vegetarian Supervillians
It’s hard to convince people to stop eating meat by making them guilty for doing so (sure hasn’t worked on me yet). It would be a lot easier if instead they felt horrific physical illness after eating meat. It turns out this is a real possibility: tick-induced meat allergy is totally a thing. Just breed the little buggers and release them en masse in major cities. Its about the only way I can imagine, short of the invention of delicious super-cheap vat-grown “meat”, that most people will stop eating animals.