MP3 (Audio) files uploaded to S3 are unplayable - how to correctly upload audio to S3?

I have a ReactJS NextJS App that generates an audioFile, blobURL and also the raw audioBlob on the front-end and passes the data via an API Route directly to AWS S3. Unfortunately, the files that are received by S3 are not playable via the console, or after download.

This is the fetch request which is attempting to send audioFile onClick:

  const submitVoiceMemo = async () => {
    try {
      await fetch('/api/createVoiceMemo', {
        method: 'PUT',
        body: audioFile
      })
    } catch (error) {
      console.error(error)
    }
  }

and this is the API route:

module.exports = requireAuth(async (req, res) => {
  try {
    AWS.config.update({
      accessKeyId: process.env.AWS_ACCESS_KEY_1,
      secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY_ID,
      region: 'us-east-2',
      signatureVersion: 'v4'
    })

    const s3 = new AWS.S3()

    const uuid = randomUUID()
    const s3Params = {
      Bucket: 'waveforms',
      Key: `voicememo/${uuid}.mp3`,
      Body: req.body,
      ContentType: 'audio/mpeg',
      ACL: 'public-read'
    }

  } catch (e) {
    res.status(500).json({ error: e.message })
  }
})

How can I correctly upload audio MP3s to S3 so they are playable in the console?