All Playlistlist data is stored on-device, and does not ever leave your device, and it is never uploaded anywhere for any reason. The same goes for Playlistlist Max. Take a look at the privacy policies of our supported music providers, though:
<ul>
  <li><a href="https://www.apple.com/legal/privacy/data/en/apple-music/">Apple Music</a></li>
  <li><a href="https://www.spotify.com/us/legal/privacy-policy/">Spotify</a></li>
</ul>
<b>Some Playlistlist Social data (profile picture, username) is PUBLIC! When you use Playlistlist Social all of your playlists are uploaded to a database managed by me and can only be viewed by friends that you allow. If the playlist you're uploading is an Apple Music playlist, the playlist cover image is uploaded to Firebase Storage and is public.</b></b>