Is there an existing issue for this?

• I have checked for existing issues https://github.com/getsentry/sentry-javascript/issues
• I have reviewed the documentation https://docs.sentry.io/
• I am using the latest SDK release https://github.com/getsentry/sentry-javascript/releases

How do you use Sentry?

Sentry Saas (sentry.io)

Which SDK are you using?

@sentry/nextjs

SDK Version

8.22.0

Framework Version

14.2.4

Link to Sentry event

https://test-application-g0.sentry.io/issues/5682136612/?project=4507729342496768

Reproduction Example/SDK Setup

sentry.server.config.ts/sentry.edge.config.ts

Sentry.init({
  dsn: dsn,
  ...,
  integrations: [
    Sentry.requestDataIntegration({
      include: { ip: true },
    }),
  ],
});

pages/api/test-error.ts

import type { NextApiRequest, NextApiResponse } from "next";

export default function handler(req: NextApiRequest, res: NextApiResponse) {
  throw new Error("text error");
}

Steps to Reproduce

1. Visit /api/test-error
2. View the created issue in Sentry

Expected Result

The IP address field should be the one contained in X-Forwarded-For or X-Real-Ip.

Actual Result

The IP address used is always ip:::ffff:127.0.0.1 (or some variant of localhost).