Array.prototype.flat() Method Breaks Application in Release Build

Problem Description

When calling Array.prototype.flat() in a react-native-windows project, the release build is broken, while the debug build runs smoothly.

Steps To Reproduce

1. As a minimal reproducible example, a component such as the following may be created:

import React from "react";
import { StyleSheet, View } from "react-native";

export default function() {
    return (
        <View style={[...[styles.content].flat()]} />
    );
}

const styles = StyleSheet.create({
    content: {
        flex: 1,
    },
});

(Alternatively, as a more complete example, the DropDownPicker component from the library react-native-dropdown-picker may be used in a project. Internally, the library calls Array.prototype.flat() in multiple places.)

2. A debug build from the project shall be created by running:

npx react-native run-windows

The expected behavior is that in the debug build, the application runs smoothly.

3. A release build from the project shall be created by running:

npx react-native run-windows --release

In the release build, the app will show a blank screen.

Expected Results

The expected behavior is that the application will show a blank screen. This depends on when the element becomes active:

• when the element is active on the initial screen, the app will start and show blank view immediately
• when the element is switched active on user interaction while the app is already running, the app will become a blank view

CLI version

10.2.2

Environment

npx react-native -v: 10.2.2
npm ls react-native-windows: react-native-windows@0.71.11
npm -v: 9.5.0
node -v: v18.15.0
msbuild version: 17.6.33815.320
<UseHermes>false</UseHermes>

Target Platform Version

10.0.19041

Target Device(s)

Desktop

Visual Studio Version

Visual Studio 2022

Build Configuration

Release

No source file or test is identified. First reproduce the issue with the provided react-native-windows 0.71.11 commands, comparing debug and release behavior with Array.prototype.flat(); done means the release build no longer becomes a blank screen while the same example remains functional.