Google released the standalone Tasks app for Android and iOS back in April 2018, which is also integrated to Calendar on the web. But now Google has integrated Tasks for Calendar's Android and iOS apps as well, allowing you to create and view tasks from a mobile on Calendar.
This integration should also eliminate the need to have the standalone Tasks app on your mobile since you can now create new tasks and view existing ones in the Calendar app.
To add a new task in Calendar from the mobile apps, simply tap on the create button in the bottom-right corner, tap on 'Task', fill in the details, and save it. Needless to say, the tasks you add to your calendar will be synced across mobile and desktop automatically.
This new feature is already rolling out for Android and iOS and should reach all G Suite customers and personal Google accounts in two weeks.