Link to the code that reproduces this issue

https://github.com/GlebKodrik/nextjs-bug

To Reproduce

1. Clone the repo and install dependencies.
2. Run the app in development mode: npm run dev.
3. Scroll to the bottom of the page — you will see two buttons: Intensive and Check.
4. Click either button → navigation happens via:

router.push(`?${params.toString()}`, { scroll: false })

• In development mode, the page does not scroll to top.

1. Build and start the app in production:

next build
next start

1. Scroll to the bottom and click either button again → the page jumps to top unexpectedly.

⚠️ Important:

• Removing loading.tsx prevents the scroll jump.
• Adding loading.tsx triggers the scroll jump again.

Current vs. Expected behavior

Current behavior: When calling

router.push(`?${params.toString()}`, { scroll: false })

the page still scrolls to the top, but only in the production build and only when a loading.tsx file exists.

Expected behavior: The page should not scroll to the top when { scroll: false } is passed, regardless of environment or presence of loading.tsx.

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 23.6.0
Binaries:
  Node: 20.17.0
  npm: 10.8.2
  Yarn: 1.22.22
  pnpm: 9.10.0
Relevant Packages:
  "next": "^15.5.2",
  "react": "19.1.0",
  "react-dom": "19.1.0"
Next.js Config:
  output: N/A

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

Loading UI and Streaming

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

next build (local)

Additional context

Additional context

• The issue seems to be tightly connected with the loading.tsx file. Without it, everything works fine.
• Might be related to how Suspense boundaries or loading.tsx trigger re-render and reset scroll state.
• Happens both locally and in production build environment.