Mystery Breakpoints When Debugging NextJS in Visual Studio Code

I've got a NextJS app that I'm running in VSC. When debugging, it seems like I'm hitting breakpoints in the /.next build folder but I can't explain why.

This is the launch.json file I'm using:

{
      "name": "Launch Next.js app",
      "request": "launch",
      "runtimeArgs": ["run", "dev"],
      "runtimeExecutable": "npm",
      "skipFiles": ["<node_internals>/**", "${workspaceRoot}/.next/**/*", "${workspaceRoot}/node_modules/**/*"],
      "type": "node"
    }

I'm guessing it's a sourcemap issue but I'm not very experienced with this, so I'm hoping someone might be able to help as it's incredibly annoying.