Meat derivatives are in a lot of products. Seasonings, sauces, etc. can hide a lot of those. You can order like a teriyaki tofu dish, for example, and most of the time you’ll be fine. But you’ll eventually run into a variety here and there that uses dashi or oyster sauce in the ingredients. Or you get kimchi and have to worry about the same thing with fish sauce. You get a bag of BBQ potato chips, there’s a chance it contains chicken. Order a cheese pizza, the sauce may still contain tiny bits of sausage. Even a vegetable soup may still use beef or chicken stock.