React does not recognize the `xmlns vuejs` prop on a DOM element. If you intentionally want it to appear in the DOM as a custom attribute, spell it as lowercase `xmlns svg js` code example

Example: vuejs does props factory function have access to vue instance

Vue.component('foo', {
  template: '<div>{{ num }}</div>',
  props: {
    func: {
      type: Number,
      default: () => this.a,
    },
  },
  data() {
    return { 
      num: this.func(),
      a: -22
    }
  }
})

new Vue({
  el: '#app',
});