The Audio Analysis API also reports a tempo_confidence and there’s a 43.2% confidence on that Adele song.

    {
      "meta": {
        "analyzer_version": "4.0.0",
        "platform": "Linux",
        "detailed_status": "OK",
        "status_code": 0,
        "timestamp": 1633650625,
        "analysis_time": 7.80526,
        "input_process": "libvorbisfile L+R 44100->22050"
      },
      "track": {
        "num_samples": 4954520,
        "duration": 224.69478,
        "sample_md5": "",
        "offset_seconds": 0,
        "window_seconds": 0,
        "analysis_sample_rate": 22050,
        "analysis_channels": 1,
        "end_of_fade_in": 0.26807,
        "start_of_fade_out": 209.58913,
        "loudness": -7.519,
        "tempo": 141.981,
        "tempo_confidence": 0.432,
        "time_signature": 4,
        "time_signature_confidence": 1,
        "key": 5,
        "key_confidence": 0.545,
        "mode": 1,
        "mode_confidence": 0.58,

        ...

    }

[1] https://developer.spotify.com/console/get-audio-analysis-tra...