[Vuejs]-Why my icon don't change when i'm clicking on ? (ionic/vue/ts)

You have onChange as a literal false, which is not reactive.

Wrap the value in a a ref to enable reactivity:

import { ref } from 'vue'

export default {
  setup() {
    return {
      //onChange: false ❌ not reactive

      onChange: ref(false) ✅
    }
  }
}