vue/no-v-for-template-key 
disallow
keyattribute on<template v-for>
- ⚙️ This rule is included in all of 
"plugin:vue/essential",*.configs["flat/vue2-essential"],"plugin:vue/strongly-recommended",*.configs["flat/vue2-strongly-recommended"],"plugin:vue/recommended"and*.configs["flat/vue2-recommended"]. 
📖 Rule Details 
This rule reports the <template v-for> elements which have key attribute.
In Vue.js 2.x, disallows key attribute on <template> elements.
Note
This rule is targeted at Vue.js 2.x. If you are using Vue.js 3.x, enable the vue/no-v-for-template-key-on-child rule instead. Don't enable both rules together; they are conflicting.
Note
If you want to report keys placed on <template> without v-for, use the vue/no-template-key rule.
🔧 Options 
Nothing.
👫 Related Rules 
📚 Further Reading 
🚀 Version 
This rule was introduced in eslint-plugin-vue v7.0.0