Using export dynamic = 'auto' opts you into dynamic rendering

Link to the code that reproduces this issue

https://github.com/MangoMarcus/nextjs-dynamic-auto

To Reproduce

1. Clone the repository. There's a seperate route for each of the options for dynamic, plus one for none.
2. Deploy to Vercel
3. Check the "Deployment summary" under the deployment.
4. The /none route is an ISR function, but /auto isn't

Current vs. Expected behavior

I expected the default for dynamic to be 'auto', but using that actually opts you in to dynamic rendering - which is not the same behavior as omitting the export altogether.

Provide environment information

Operating System:
  Platform: macOS
  Chip: Apple M1 Pro
  Version: macOS 14.4
Binaries:
  Node: 20.2.0
  npm: 9.6.6
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 14.2.3
  eslint-config-next: N/A
  react: 18.3.1
  react-dom: 18.3.1
  typescript: 5.4.5
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Performance, Runtime

Which stage(s) are affected? (Select all that apply)

Vercel (Deployed)

Additional context

Start with the linked nextjs-dynamic-auto reproduction, deploy it to Vercel, and compare the /auto and /none routes in the deployment summary. Trace the route-segment dynamic configuration and rendering behavior; the issue is done when explicitly setting dynamic='auto' has the intended documented behavior relative to omitting the export.