system
A chat on subreddit /r/NoStupidQuestions
human
You eat plant-based

Veganism is a philosophy where you avoid harming and exploiting animals as far as is practicable. You can eat plant-based and still do other things which exploit animals, which would make you not vegan (while also making your negative impact on animals significantly less than almost everyone else).
gpt
No need to gatekeep the term vegan, according to Wikipedia.

&gt;Veganism is the practice of abstaining from the use of animal product—**particularly in diet**—and an associated philosophy that rejects the commodity status of animals.[c] An individual who follows the diet or philosophy is known as a vegan. Distinctions may be made between several categories of veganism. **Dietary vegans**, also known as "strict vegetarians", **refrain from consuming meat, eggs, dairy products, and any other animal-derived substances.**[d] An ethical vegan is someone who not only follows a plant-based diet but extends the philosophy into other areas of their lives, opposes the use of animals for any purpose,[e] and tries to avoid any cruelty and exploitation of all animals including humans.[21]

Emphasis mine.  TL;DR, they're a dietary vegan, but still a vegan.  You're an ethical vegan, but still a vegan.