Error during deployment: password authentication failed for user 'default'

I have a Next.js app I’m building, maintained in GitHub, and running on Vercel. When I run a deployment in Vercel I’m getting the following error:

Deployment Details…

Error querying the database: ERROR: password authentication failed for user 'default'
    at ni.handleRequestError (/vercel/path0/node_modules/@prisma/client/runtime/library.js:124:7090)
    at ni.handleAndLogRequestError (/vercel/path0/node_modules/@prisma/client/runtime/library.js:124:6206)
    at ni.request (/vercel/path0/node_modules/@prisma/client/runtime/library.js:124:5926)
    at async l (/vercel/path0/node_modules/@prisma/client/runtime/library.js:129:10023)
    at async /vercel/path0/.next/server/chunks/26.js:1:913
    at async invokeCallback (/vercel/path0/.next/server/chunks/859.js:1:57958)
    at async EventPage (/vercel/path0/.next/server/app/event/[slug]/page.js:1:3362) {
  clientVersion: '5.6.0',
  errorCode: undefined

I’m unclear why this password authentication failure is occurring. Any thoughts about what’s happening here?

It looks like Prisma is missing the auth info it needs. Is the project missing an environment variable?