Alright, so I'm posting here because I genuinely have no more leads to follow.

I am deploying a project with the following architectural context:

- Turborepo v2.0.3
- PNPM v9.2.0 (w/ Workspaces)
- NextJS Site v14.2.3
- Node v20.2.0

The NextJS site lives at ./apps/dotcom relative to the project root.

I can successfully build everything using turbo run build --filter="@scope/dotcom..." and it logs the correct scope for all internal deps to be pre-built as well.

When building the NextJS site (everything else has successfully built up to this point) I get the following error stacktrace (trimmed for brevity):

@scope/dotcom:build: unhandledRejection ReferenceError: Headers is not defined
@scope/dotcom:build:     at Object.<anonymous> (/vercel/path0/node_modules/.pnpm/next@14.2.3_react-dom@18.3.1_react@18.3.1__react@18.3.1/node_modules/next/dist/server/web/spec-extension/adapters/headers.js:32:30)
...
@scope/dotcom:build:  ELIFECYCLE  Command failed with exit code 1.
@scope/dotcom:build: ERROR: command finished with error: command (/vercel/path0/apps/dotcom) /pnpm9/node_modules/.bin/pnpm run build exited (1)
@scope/dotcom#build: command (/vercel/path0/apps/dotcom) /pnpm9/node_modules/.bin/pnpm run build exited (1)
  Tasks:    5 successful, 6 total

It does not appear to be a common issue so I suspect I have done something in my own configs or hit a strange edge case.

Some things I have investigated, but always willing to double check and verify:
- I do not have any flags disabling built-in fetch for Node
- The build step logs v20.12.2 which is notably different to the v20.12.0 on my local. Currently looking into this.