Inaccurate sourcemaps for sources under node_modules

Verify canary release

• I verified that the issue exists in the latest Next.js canary release

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #85~20.04.1-Ubuntu SMP Mon Jul 17 09:42:39 UTC 2023
Binaries:
  Node: 18.16.0
  npm: 9.5.1
  Yarn: 1.22.18
  pnpm: 8.6.7
Relevant Packages:
  next: 13.4.12
  eslint-config-next: N/A
  react: 18.2.0
  react-dom: 18.2.0
  typescript: N/A
Next.js Config:
  output: N/A

Which area(s) of Next.js are affected? (leave empty if unsure)

No response

Link to the code that reproduces this issue or a replay of the bug

https://github.com/replayio/nextjs-inaccurate-sourcemaps

To Reproduce

• npm run build
• upload .next/static/chunks/main-26f0defd1fe4aedb.js[.map] to https://evanw.github.io/source-map-visualization/
• select webpack://_N_E/node_modules/@swc/helpers/esm/_interop_require_wildcard.js as the original source
• for comparison, upload .next/static/chunks/pages/_app-27374a655d3a2ebe.js[.map] to https://evanw.github.io/source-map-visualization/ and select webpack://_N_E/src/_interop_require_wildcard.js

Alternatively, you can look at these sourcemaps here:

• webpack://_N_E/node_modules/@swc/helpers/esm/_interop_require_wildcard.js: https://app.replay.io/recording/5072126e-507f-43d9-8c9e-889ad2bfd0dd/sourcemap/o4-80-c194bb-ec5646
• webpack://_N_E/src/_interop_require_wildcard.js: https://app.replay.io/recording/5072126e-507f-43d9-8c9e-889ad2bfd0dd/sourcemap/o6-6-c194bb-5d30d7

Describe the Bug

I've noticed that the sourcemaps produced by Next.js are inaccurate for some sources, making it impossible for debuggers to show scopes with original (rather than generated) variable names.
This seems to be the case for all sources under node_modules.
To reproduce the problem I've used create-next-app to create an app and copied node_modules/@swc/helpers/esm/_interop_require_wildcard.js to src/_interop_require_wildcard.js. This is what a sourcemap visualizer shows for these two copies of the same source:

node_modules/@swc/helpers/esm/_interop_require_wildcard.js:

src/_interop_require_wildcard.js:

Expected Behavior

Sourcemaps for sources under node_modules should be accurate.

Which browser are you using? (if relevant)

No response

How are you deploying your application? (if relevant)

No response

Start with the linked reproduction repository and run npm run build. Compare the sourcemaps for .next/static/chunks/main-26f0defd1fe4aedb.js and pages/_app-27374a655d3a2ebe.js, focusing on the node_modules/@swc/helpers/esm/_interop_require_wildcard.js and src/_interop_require_wildcard.js sources. Done means sources under node_modules produce accurate mappings like the copied source.