PrimeVue v-tooltip - Need help understanding error

I'm testing out PrimeVue. Created a simple timestamp template that is being imported and displayed in the main App.vue template. See the following code. timestamp and local_timestamp show up correctly in the template. However, the tooltip is not working. If I use a string instead of the computed property, it shows up fine. The console gives the following error: main.js:29 TypeError: r.value.value.trim is not a function

That is referencing the following line of code from PrimeVue's Tooltip component. https://github.com/primefaces/primevue/blob/master/packages/primevue/src/tooltip/Tooltip.js#L25

Any idea what I'm missing here?

<template>
  <div v-tooltip="{ value: local_timestamp }">
    {{ timestamp }}
  </div>
  {{ local_timestamp }}
</template>

<script setup>
import { computed, defineProps } from 'vue'

const props = defineProps({
  timestamp: {
    type: String,
    required: true
  }
})

const local_timestamp = computed(() => {
  return new Date(props.timestamp)
})
</script>

I've been referencing the PrimeVue documentation here: https://primevue.org/tooltip/