Link to the code that reproduces this issue

https://github.com/sdoomz/nextjs-sass-hmr-not-applied-bug

To Reproduce

1. git clone https://github.com/sdoomz/nextjs-sass-hmr-not-applied-bug
2. npm install
3. npm run dev
4. open http://localhost:3000 and follow instructions

Current vs. Expected behavior

Current behavior:
Styles are cleared up after HMR in lazy component

Expected behavior:
Styles should be preserved after HMR in lazy component

Provide environment information

Operating System:
  Platform: darwin
  Arch: x64
  Version: Darwin Kernel Version 24.3.0: Thu Jan  2 20:22:00 PST 2025; root:xnu-11215.81.4~3/RELEASE_X86_64
  Available memory (MB): 32768
  Available CPU cores: 8
Binaries:
  Node: 23.11.0
  npm: 10.9.2
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 15.3.1 // Latest available version is detected (15.3.1).
  eslint-config-next: 15.3.1
  react: 19.1.0
  react-dom: 19.1.0
  typescript: 5.8.3
Next.js Config:
  output: N/A

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

Lazy Loading

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

next dev (local)

Additional context

The issue started to reproduce since next@15.0.0, only legacy npm run dev is affected, no issue for npm run dev --turbo.