DependentKeyCompat

controllers.application\.js

import Controller from '@ember/controller';
import { tracked } from '@glimmer/tracking';
import EmberObject, { action, computed, observer } from '@ember/object';
import { dependentKeyCompat } from '@ember/object/compat';

class Foo extends EmberObject {
  @tracked _tag = '';
  
  @dependentKeyCompat
  get id() {
    this._tag; // consume tag
    return this._id;
  }
  set id(v) {
    this._tag = '';
    this._id = v;
  }
}

const Bar = Foo.extend({
  appName: computed('id', function() { return this.id }),
  foo: observer('id', function() { console.log('id', this.id); }),
});

export default class ApplicationController extends Controller {
  data = Bar.create();

  get appName() {
  	return this.data.appName
  }

  @action update() {
    this.data.id = 'abc';
  }
}

templates.application\.hbs

<h1>Welcome to {{this.appName}}</h1>
<br>
<button {{on 'click' this.update}}>Update</button>
<br>
{{outlet}}
<br>
<br>

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"
  }
}