vue 3 - $emit not defined upon instance of new Vue application

Question

I have a Laravel 10 application and I am trying to register a global function in Vue 3. I want to be able to call a flash function from anywhere in my application. I am trying to create a Vue instance and then call $emit on that instance. However, when I call the method in Chrome devtools, I get a '$emit is not a function' message. In Vue 2 you could new up an instance of Vue using window.events = new Vue() but apparently that changed in Vue 3

this is in my bootstrap.js file:

import {createApp } from 'vue';
import Flash from "@/Components/Flash.vue";
window.events = createApp(Flash);
window.flash = function (message, level = 'success') {
    window.events.$emit('flash', { message, level });
};

Flash.vue

<template>
    <div class="alert alert-flash"
         :class="'alert-'+level"
         role="alert"
         v-show="show"
         v-text="body">
    </div>
</template>

<script>
export default {
    props: ['message'],
    data() {
        return {
            body: this.message,
            level: 'success',
            show: false
        }
    },
    created() {
        if (this.message) {
            this.flash();
        }
        window.event.$on(
            'flash', data => this.flash(data)
        );
    },
    methods: {
        flash(data) {
            if (data) {
                this.body = data.message;
                this.level = data.level;
            }
            this.show = true;
            this.hide();
        },
        hide() {
            setTimeout(() => {
                this.show = false;
            }, 3000);
        }