There is no such thing as an "original" raw file. A raw file, if you could see it, would be a very dark, very compressed and flat monochrome image. That's how the sensor records it, and that's what the raw file is. You wouldn't like it. To produce a useful color image, the raw file has to be processed. This can happen in the camera, in which case the output is a jpeg, processed according to a formula preset by the camera manufacturer. Or you can process it yourself in a raw processor, in which case you have actual control over the finished result. Windows Photos does not show you the raw data. It shows you a small camera-processed jpeg preview, embedded in the file. It is also, as Akash points out, not color managed and does not use your monitor profile to correct for your display. The whole point of shooting raw is to give you control over how you want the file to look. If you prefer the camera jpeg, there's no point in shooting raw at all. You should also know that many cameras have automatic functions to lighten up the shadows. Nikon, for instance, calls this D-lighting. This is again just a processing formula - the sensor data as captured are the same. Lightroom/ACR will ignore all these camera settings, because you can usually produce better results there.
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