[appDir]: Dynamic pages with dynamic parameters rendered as static by default

Why this is a good first issue

Dynamic page rendering behavior mismatch with documented expectations.

AI Summary

The issue reports that dynamic pages with parameters are incorrectly rendered as static despite using dynamic functions like cookies. The expected behavior is documented, and a maintainer indicates this may already be fixed in newer versions. The scope appears limited to dynamic rendering logic in the app directory.

Issue Description

Verify canary release

I verified that the issue exists in the latest Next.js canary release

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #1 SMP Wed Nov 23 01:01:46 UTC 2022
Binaries:
  Node: 18.13.0
  npm: 9.3.1
  Yarn: 1.22.19
  pnpm: N/A
Relevant packages:
  next: 13.1.5-canary.2
  eslint-config-next: N/A
  react: 18.2.0
  react-dom: 18.2.0

Which area(s) of Next.js are affected? (leave empty if unsure)

App directory (appDir: true)

Link to the code that reproduces this issue

https://github.com/peterjuras/nextjs-13-wrong-static-rendering

To Reproduce

Clone the repository
Run yarn build

Describe the Bug

In my project, the [slug]/page is rendered as static, although the cookies function is called. According to the docs, this should mark the page as dynamic.

Expected Behavior

The [slug] page should be marked as dynamic.

Which browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)