New Twiddle

controllers.application\.js

import Controller from '@ember/controller';
import { tracked } from '@glimmer/tracking';

export default class ApplicationController extends Controller {
  queryParams = ['myArray'];

  // The default value being an array is important. Changing this
  // to anything else fixes the problem.
  @tracked myArray = [];
}

templates.application\.hbs

{{!--
  Adding @query={{hash myArray=(array "non" "empty")}} fixes the issue.
  However, adding @query={{hash}} or @query={{hash myArray=(array)}} does not.
--}}
<LinkTo @route="application">
  a link that uses the QP's default array value, click to trigger bug
</LinkTo>

<br>

{{!--
  Accessing the QP-backed tracked property a second time is required.
  It can be passed to a helper or just rendered like this. If using helpers,
  it doesn't matter if the value is used inside the helper or not.
  Removing this access fixes the issue.
--}}
{{this.myArray}}

<br>

{{!--
  Clicking the link is unimportant. The issue happens on any subsequent
  re-render. The following is unrelated to the reproduction, except to give
  some other means to trigger a re-render.
--}}
{{input value=this.value}}

<br>

{{this.value}}

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"
  }
}