Computed Bug

controllers.application\.js

import Controller from '@ember/controller';
import Changeset from "ember-changeset";
import {tracked} from "@glimmer/tracking";
import {action, get, computed, defineProperty} from "@ember/object";

export default class ApplicationController extends Controller {
  appName = 'Ember Twiddle';

	get __val(){
    return get(this.model, "greeting.de")
  }
  
  // Validated Form current implementation
	constructor(...args){
    super(...args)
    defineProperty(
      this,
      "_val",
      computed("model.greeting.de", function(){
        return get(this.model, "greeting.de")
      })
    )
  }

	model = new Changeset({greeting:{de: "Hallo"}})

	@action 
	update (property, {target:{value=""}={}}={}) {
    this.model.set(property, value)
  }
}

templates.application\.hbs

<p>
<p>Computed: {{this._val}}</p>
<p>Getter: {{this.__val}}</p>
<input value={{this.model.greeting.de}} {{on "input" (fn this.update "greeting.de")}}/>
</p>

twiddle\.json

{
  "version": "0.17.1",
  "EmberENV": {
    "FEATURES": {},
    "_TEMPLATE_ONLY_GLIMMER_COMPONENTS": false,
    "_APPLICATION_TEMPLATE_WRAPPER": true,
    "_JQUERY_INTEGRATION": true
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.js",
    "ember": "3.18.1",
    "ember-template-compiler": "3.18.1",
    "ember-testing": "3.18.1"

  },
  "addons": {
    "@glimmer/component": "1.0.0", 
    "ember-changeset": "3.12.0",
    "ember-changeset-validations": "3.13.0"
 
  }
}