Why does a Suno song speed up or slow down?

A Suno song can contain tempo drift in the generated audio itself. The track may begin near the requested BPM, then gradually run faster or slower later in the song. Adding an exact BPM to a prompt does not guarantee that every generated section will follow one fixed grid.

If you want to keep that generation, use the Suno Tempo Fixer to correct gradual BPM changes before adding drums, stems, or DAW edits.