Helper Precedence Issue

components.my-child.js

import Ember from 'ember';

export default Ember.Component.extend({
});

components.my-parent.js

import Ember from 'ember';

export default Ember.Component.extend({
  init() {
    this._super(...arguments);
    this.set('changeset', 'My Changeset');
    this.set('otherProp', 'Other Prop');
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

helpers.changeset.js

import Ember from 'ember';

export function changeset(params/*, hash*/) {
  return `Changeset helper: ${params[0]}`;
}

export default Ember.Helper.helper(changeset);

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{my-parent}}
<br>
<br>

templates.components.my-child.hbs

{{this.changeset}}

templates.components.my-parent.hbs

<p>
Curly-bracket invocation:
{{my-child changeset=changeset}}
</p>

<p>
  Angle-bracket invocation:
  <MyChild @changeset={{changeset}} />
</p>

<p>
  Angle-bracket invocation with <code>this.</code>:
  <MyChild @changeset={{this.changeset}} />
</p>

<p>
  Helper invocation:
  {{changeset "in"}}
</p>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}