[PPR] Dynamic route segment params are double encoded

Link to the code that reproduces this issue

https://github.com/marmalade-labs/ppr-double-encode

To Reproduce

1. Navigate to https://ppr-double-encode.vercel.app/hello%20world

(note: this bug only shows when deployed to Vercel, not when running locally).

Current vs. Expected behavior

I expected hello%20world to be displayed but instead we see hello%2520world. When running locally or with PPR disabled, it works as expected.

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #1 SMP PREEMPT_DYNAMIC Fri, 04 Oct 2024 21:51:11 +0000
  Available memory (MB): 62093
  Available CPU cores: 16
Binaries:
  Node: 22.9.0
  npm: 10.8.3
  Yarn: 1.22.22
  pnpm: 9.12.1
Relevant Packages:
  next: 15.0.0-canary.181 // Latest available version is detected (15.0.0-canary.181).
  eslint-config-next: N/A
  react: 19.0.0-rc-2d16326d-20240930
  react-dom: 19.0.0-rc-2d16326d-20240930
  typescript: 5.3.3
Next.js Config:
  output: N/A

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

Partial Prerendering (PPR)

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

Vercel (Deployed)

Additional context

@wyattjoh, @ztanner - thought you might find this one interesting !