Peta constantly does these stupid stunts like get mad at animal crossing for including fishing, shit like that. They're also portrayed as the "typical vegan" throughout the media so anything you bring up veganism many people think of Peta and therefore those "crazy vegoons" stunts. Just a constant laughing stock ("People Eating Tasty Animals") and as a result nobody takes veganism as a whole seriously either. Sometimes they do things that are kinda good but given their public perception either they're an op or their leadership is playing directly into the hands of the animal ag industry.

Edit: not to mention their horrendous takes on PBC. You're not a vegan org if you encourage people to give KFC money because they have vegan chicken substitute