NextAuth custom signin page only finding providers when running locally

Hey, would appreciate anyone who can shed some light on why this is happening - in the screenshots I've attached my authOptions from auth.ts (with the signin route and the Discord provider visible), and a snippet from my signin.tsx page. When running locally clickin the signin button displays a "Sign in with Discord button" as expected (3rd screenshot). When I deploy to Vercel (https://www.hyhy.gg/) the "Sign in with Discord button" doesn't appear. Am I missing something obvious here? I have another t3 application where this worked as expected without issue.