Output of FFmpeg has a "slow motion" part - what is it and how to avoid?
Your source is variable frame-rate with a peak rate of 120 and an average rate of close to 60. Editors tend to want constant frame rate streams. If you can interpret your whole transcoded file as 120 fps, then you should get the expected result. Alternatively, you can preserve the original variable frame rate,

ffmpeg -i test-source.mov -vsync vfr test-result.mov


or transcode to a constant 60 fps,

ffmpeg -i test-source.mov -r 60 test-result.mov