Route interception broken in production mode, although working in development mode

[IddanCF]

Link to the code that reproduces this issue

https://github.com/IddanCF/repro-next-intercept

To Reproduce

1. Start the application in dev mode (npm run dev)
2. Open http://localhost:3000/, click the 'Interception link' to see the modal
3. Now run the project in production mode (npm run build npm start)
4. Click the 'interception link'. It navigates to the page instead of showing the modal

Current vs. Expected behavior

I expected the modal to keep working similar to how it does in dev mode, also in production mode.

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 23.4.0: Fri Mar 15 00:12:25 PDT 2024; root:xnu-10063.101.17~1/RELEASE_ARM64_T6030
  Available memory (MB): 18432
  Available CPU cores: 11
Binaries:
  Node: 20.11.0
  npm: 10.5.2
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 14.2.3 // Latest available version is detected (14.2.3).
  eslint-config-next: N/A
  react: 18.3.1
  react-dom: 18.3.1
  typescript: 5.1.3
Next.js Config:
  output: N/A

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

Parallel & Intercepting Routes

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

next start (local), Vercel (Deployed)

Additional context

The [slug] at the root, and generateStaticParams in layout seem to be required for this bug to occur.

I also added another link without route interception to make sure it is not a problem with the @modal slot.

_NEXT-3295