When I used to maintain a discord music bot, it used to stream from YouTube. For Spotify urls to work though, I had to get YouTube search to work reliably. One trick which I found worked well was including the Spotify URL in the YouTube search along with the song name, artist name, etc. This helped quite a bit with picking out the "official" youtube video, since the official one often includes Spotify links in the video description, which YouTube search also matches against.