[Vuejs]-Within my Vue 3 component using Vueify, how do I conditionality render different images?

Yuu can use instead:

<v-img
  contain
  :src="threesMMRToRankImage(userinfo.threesMMR)"
/>

And remove from data()

threesRankImage: this.threesMMRToRankImage(this.userinfo.threesMMR),

This last line is calling this.userinfo.threesMMR which is just declared in the same data() method body