vue/no-multiple-template-root 
disallow adding multiple root nodes to the template
- ⚙️ 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 checks whether template contains single root element valid for Vue 2.
🔧 Options 
Nothing.
🚀 Version 
This rule was introduced in eslint-plugin-vue v7.0.0