Using <script setup> and volar v0.28.6, this works fine:

<template>
  <p>{{ someVar }}</p>
</template>

<script lang="ts" setup>
import { ref } from 'vue';
const someVar = ref(3);

const emit = defineEmits<{
  (e: 'change', id: number): void;
}>();
</script>

But when using an interface with defineEmits, no variables/functions/props/etc can be found by TS anymore:

And doing the same thing with defineProps works with no problems