Vue version

3.2.47

Link to minimal reproduction

https://stackblitz.com/edit/vue-urpeut?file=src/App.vue

Steps to reproduce

step1: define a component Test.vue, create a slot for fallback content 'BBB'

<template>
  <div>
    <slot> BBB </slot>
  </div>
</template>

step2: using Composition API by