Conveniently forgetting that the only reason a healthy nutritionally balanced vegan or vegetarian diet is even remotely possible is due to globalised trade and access to internationally produced and shipped vegetables.
To maintain a nutritionally complete vegan diet for an individual year round actually requires far more use of fossil fuels and directly released carbon emissions due to limited seasonality and local accessibility than a cow produces for the same nutrient density and complexity locally.
Here’s a “fun” fact, first world demand for fruit and grain variety has out priced primary sources of food for local populations in third world countries including things like lentils, quinoa, and avocados.
Or that nutritional deficiencies caused by incorrectly managed vegan diets are why doctors in Italy and Belgium are pushing for it to become illegal to feed children vegan diets, because the number of malnourished and dead children of vegan parents are rising in those nations.