Every 50 tracks or so, at a guess, the music goes silent for the last ~30 seconds of the track.
The playhead keeps moving (looking in both the Spotify and Sonos desktop apps). If I don’t do anything, there will be ~30 seconds of silence, then the next track will play correctly. If I rewind a few seconds, playback will resume and it will play through to the end of the track correctly, no silence.
I listen mostly using Spotify Connect so I don’t know if this is specific to that mechanism, or something that affects other services.