This is an improved version of the basic solution.
Some of the improvements:
<form>to capture submission of new tasks. This will handle both Enter keys and "Submit" button clicks.
<input>s should be labelled either via
aria-labelattributes. Since the original markup doesn't contain a
<label>, we can add
aria-liveregion can be added to inform about the newly-added task. There is unlikely enough time to do this during an interview but you will get bonus points for mentioning it. Read more about ARIA live regions on MDN.
<link>) and ensure there's no XSS.
<input>is cleared after a task is added.