New Twiddle

components.my-component\.js

import Component from '@ember/component';
import { run } from '@ember/runloop';
import { get, set } from "@ember/object"

export default Component.extend({
  isEditing: true,

  actions: {
  	save() {
    	this.doSave?.()
      
      run(this, () => {
      	set(this, 'isEditing', false);
      })
    }
  }
});

controllers.application\.js

import Controller from '@ember/controller';

export default Controller.extend({
	actions: {
  	saveAttr() {
   		console.log('save attr');
    }
  }
});

templates.application\.hbs

{{#my-component doSave=(action "saveAttr") as |foo|}}
	<div>{{if foo.isEditing "true"}}</div>
	<button onclick={{action foo.doSave}}>Save</button>
{{/my-component}}

templates.components.my-component\.hbs

{{yield (hash isEditing=isEditing doSave=(action "save"))}}

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": "2.18.2",
    "ember-template-compiler": "2.18.2",
    "ember-testing": "2.18.2"
  },
  "addons": {
    "@glimmer/component": "1.0.0",
    "ember-data": "2.18.5"
  }
}