[HELP] What noise is that?

[Selur]

How can I understand if files are telecined?

You look for pattern if you bob the content, read: [INFO] Interlacing patterns

after can I put up again the FR for original smoothness?

You could add interpolated frames: "Filtering->Vapoursynth->Frame->Interpolation->Frame Interpolation" (on Mac, there are way less available methods for this, than on Windows, especially with a modern gpu and vs-mlrt or torch add-on).

Obviously: If you have a real 29.97fps source (with 29.97 unique non-blended frames) and you remove frames, you will lose motion smoothness and there is nothing you can do about it.

Cu Selur