What problem does this feature solve?

why refs value changed from array(vue2) to single(vue3)

What does the proposed API look like?

why refs value changed from array(vue2) to single(vue3)

What is your issue? Provide some more explaination or examples please?

in vue2 $refs.items is [li#1, li#2, li#3]

<div id="app">
    <ul>
        <li ref="items" v-for="item in items" :id="item" :key="item">{{item}}</li>
    </ul>
</div>
<script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
<script>
    var app = new Vue({
    el: '#app',
    data: {
        message: 'Hello Vue!',
        items:[1,2,3]
    },
    mounted: function () {
        console.log(this.$refs.items) //[li#1, li#2, li#3]
    }
    })
</script>

in vue3 $refs.items is li#3

<div id="app">
    <ul >
        <li ref="items" v-for="item in items" :id="item" :key="item">{{item}}</li>
    </ul>
</div>
<script src="https://unpkg.com/vue@next"></script>
<script>
  const app = Vue.createApp({
        data() {
            return {
                items:[1,2,3]
            }
        },
        mounted: function () {
                console.log(this.$refs.items) // <li id="3"></li>
        }
    })
    app.mount('#app')
</script>

See https://github.com/vuejs/vue-next/issues/1166