Lemmy does not show you personalized content. Your feeds (All, Subscribed, Local) can be sorted by a couple of basic algorithms such as "New", "Top Day", "Controversial", or "Active". Vegan stuff seems to do well on Active because people are commenting, even though it doesn't get the most upvotes.
You can try out the Subscribed tab or block a community or member therein. If the issue persists, you can contact an admin of your instance and in the mean time think about why you're so upset about a simple dish.