If a person isn't vegan, it's not what they eat, but who. Some people don't give a fuck about other people being racist, not caring about shit is the norm.
Those were two very interesting sentences you put together.
There are some studies that show mycelium may show signs of sentient behavior. Also, trees and plants are shown to communicate and warn other plants of dangers. Heck, even trees are known to leverage mycelium networks to communicate.
I guess the question is: Who the heck have you been eating?
Any argument for plant sentience is an argument for veganism since according to the USDA, animals consume over 70% of soy and 40% of corn in the US (humans only consume 10% of corn directly).
Corn and soy are the two largest crops.
Not only does buying animal products kill the animal for that product, but amplifies crop deaths from all the crops they are fed and are inefficiently converted to flesh.
You can be vegan and not eat mushrooms. 95% of plant biologists are in agreement plants are not sentient. If they were, still makes sense to be vegan.