Okay so the network monitor showing a constant 180Kbps upload when I played music through was Spotify was due to the Multicast/RTP sender being enabled in the PulseAudio preferences. I find that out when I noticed that the porblem was not limited to just spotify web or just any internet music site but the transfer happened even if I played music locally offline. Didn't took much to figure out the culprit was RTP when I knew the problem was just audio output related.
cc @freemo