v-model.description.capitalize这段为啥又不行了？运行不出来-CFANZ编程社区

<!DOCTYPE html>
<div id="v-model-example" class="demo">
   <my-component v-model.description.capitalize="bookTitle"></my-component>
   {{ bookTitle }}
</div>

<script src="https://unpkg.com/vue@next"></script>
<script>
    const app = Vue.createApp({
      data() {
     return {
         bookTitle: ''
       }
  },
    });
    app.component('my-component', {
    props: ['description', 'descriptionModifiers'],
  emits: ['update:description'],
  template: `
    <input
      type="text"
      :value="description"
      @input="$emit('update:description', $event.target.value)">
      `,
      created() {
    console.log(this.descriptionModifiers) // { capitalize: true }
  }
   }).mount('#v-model-example')
</script>

改了一下，还不对

<!DOCTYPE html>
<div id="v-model-example" class="demo">
   <my-component v-model.description.capitalize="bookTitle"></my-component>
   {{ bookTitle }}
</div>

<script src="https://unpkg.com/vue@next"></script>
<script>
    const app = Vue.createApp({
      data() {
     return {
         bookTitle: ''
       }
  },
    });
    app.component('my-component', {
   
    props: {
      description: String,
      descriptionModifiers: {
             default: () => ({})
             }
  },
  emits: ['update:description'],
  template: `
    <input
      type="text"
      :value="description"
      @input="$emit('update:description', $event.target.value)">
      `,
      created() {
    console.log(this.descriptionModifiers) // { capitalize: true }
  }
   }).mount('#v-model-example')
</script>

不知道为啥，不知道怎么改