After deploying Next.js SSR from AWS Amplify getting 404 error

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- [X] I have checked to see if my question is addressed in the [FAQ](https://github.com/aws-amplify/amplify-hosting/blob/master/FAQ.md).
- [X] I have [searched for duplicate or closed issues](https://github.com/aws-amplify/amplify-hosting/issues?q=is%3Aissue+).
- [X] I have read the guide for [submitting bug reports](https://github.com/aws-amplify/amplify-hosting/blob/master/CONTRIBUTING.md).
- [X] I have done my best to include a minimal, self-contained set of instructions for consistently reproducing the issue.
- [X] I have removed any sensitive information from my code snippets and submission.

### App Id

NEW_APP

### AWS Region

ap-southeast-1

### Amplify Hosting feature

Redirects, SSR

### Frontend framework

Next.js

### Next.js version

13.5.4

### Next.js router

App Router

### Describe the bug

My code is in specific folder . I have written the amplify.yml with specific "appRoot" directory.Even though my build and deploy get succeeded , when accessing I am getting 404 page not found

After building and deploying this is the error


### Expected behavior

If we are specifying appRoot path it should pick up the pages from the specific path of .next, but it is not taking

### Reproduction steps

Put the code in a specific path and specific the appRoot path in amplify.yml . After that build and deploy and access the url

### Build Settings

```yaml
This is my amplify.yml
version: 1
appRoot: src/ui
frontend:
phases:
preBuild:
commands:
- ls
- pwd
- npm ci
- ls
build:
commands:
- npm run build
postBuild:
commands:
- ls
- pwd
artifacts:
baseDirectory: .next
files:
- '**/*'
cache:
paths:
- node_modules/**/*
```

### Log output

This staging.d3qoyhgf3tt33g.amplifyapp.com page can’t be foundNo web page was found for the web address: https://staging.d3qoyhgf3tt33g.amplifyapp.com/

### Additional information

_No response_

Start with the reported amplify.yml, especially appRoot: src/ui and the .next artifacts baseDirectory, then compare the successful build output with the deployed root URL in the issue. Done means a Next.js 13.5.4 App Router deployment using this layout loads the application instead of returning a 404.

Written by the indexing model from the issue text.