When using refs with v-for, the component / DOM nodes are stored as an array directly to the variable name so you don’t need to use index number in the ref name. So you can do this:
<list-item
v-for="item in items"
:key="item.id"
:value="item.text"
ref="items"
/>
And use the refs in your component like this:
this.$refs.items[index]
Also note that the refs may not be in order and would need to be handled in a different way which is a completely different issue. You can follow that here: https://github.com/vuejs/vue/issues/4952