Discussion on: Re-render React.js Child Component By Passing Object Prop

You are using useState in an unusual way...

I would rewrite this as:

import React, { useState } from 'react';

const Quiz = () => {

    const [time, setTime] = useState(30);

    function goToNext(){
      setTime(30);
      ...
    }

    return (
      <>
        <Countdown time={time} onComplete={onComplete} />
        <Question current={1} />
      </>
    )

});

The article you linked to is for an older way of using React, the move to hooks (which you are using) addresses many of the concerns in it.

Without having more of the code its hard to help more. Feel free to send me a message if you want more help etc.