Hi @bkstok
Welcome to the Auth0 Community!
Depending on the technology used, with Next.js you could be able to decode the JWT header, but not the payload, on the https://jwt.io/ website. Although this following Community post does not tackle Vercel directly, it still goes over some issues with decoding the appSession cookie and I recommend that you look over it.
Allow me to link some other pages that could prove useful in this case:
- @auth0/nextjs-auth0: Successful login but no session (on vercel)
- How to Deploy a Next.js App Secured By Auth0 to Vercel
- GitHub - vercel/flags: Flags SDK by Vercel
Let us know if these resources helped resolve the issue!
Gerald