request host header is [::]:3000 in middleware when redirecting in server action

### Link to the code that reproduces this issue https://github.com/kevinmitch14/redirects ### To Reproduce 1. Start application npm run build + start 2. Press submit button to trigger redirect 3. View console logs ### Current vs. Expected behavior Current: request host header is [::]:3000 Expected: request host header is localhost:3000 ### Provide environment information ```bash Operating System: Platform: darwin Arch: arm64 Version: Darwin Kernel Version 23.0.0: Fri Sep 15 14:41:43 PDT 2023; root:xnu-10002.1.13~1/RELEASE_ARM64_T6000 Available memory (MB): 16384 Available CPU cores: 10 Binaries: Node: 20.9.0 npm: 10.1.0 Yarn: 1.22.19 pnpm: 8.15.1 Relevant Packages: next: 14.2.0-canary.0 // Latest available version is detected (14.2.0-canary.0). eslint-config-next: N/A react: 18.2.0 react-dom: 18.2.0 typescript: 5.1.3 Next.js Config: output: N/A ``` ### Which area(s) are affected? (Select all that apply) App Router, Middleware / Edge (API routes, runtime) ### Which stage(s) are affected? (Select all that apply) next dev (local), next build (local) ### Additional context --- Host looks to be okay when deployed to Vercel. However I wasn't able to test this with subdomains. I've tracked it down to this PR https://github.com/vercel/next.js/pull/62561. Using the canary version before this logs host as localhost:3000. For context, our app is a multi tenant app, each tenant lives on a subdomain. We use rewrites to handle this. To get the subdomain, we use the request host header.