Link to the code that reproduces this issue

https://github.com/ctolkien/next-route-params-issue

To Reproduce

Browse to /products/foo%20bar

This code is running const { productId } = await params; in both the default export function as well as the generateMetaData function. Observe in the server logs that there are differences in what decoding has taken place:

[Page] raw productId: "foo%20bar"
[Page] char codes: [
  102, 111, 111, 37,
   50,  48,  98, 97,
  114
]
[generateMetadata] raw productId: "foo bar"
[generateMetadata] char codes: [
  102, 111, 111, 32,
   98,  97, 114
]

The generateMetadata version has been url decoded, where as the one in another function has not.

This was introduced in 16.2.0-canary.54, seemingly by #90249. I do not think the change of behaviour was intentional.

Current vs. Expected behavior

The results of await params should be consistent.

Provide environment information

Operating System:
  Platform: win32
  Arch: x64
  Version: Windows 11 Enterprise
  Available memory (MB): 65422
  Available CPU cores: 16
Binaries:
  Node: 24.13.1
  npm: 11.8.0
  Yarn: N/A
  pnpm: 11.9.0
Relevant Packages:
  next: 16.3.0-preview.5 // Latest available version is detected (16.3.0-preview.5).
  eslint-config-next: N/A
  react: 18.3.1
  react-dom: 18.3.1
  typescript: 5.9.3
Next.js Config:
  output: N/A

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

Dynamic Routes

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

next dev (local), Other (Deployed)

Additional context

No response