There's no such thing as a "no adjustments" viewable image on a screen from a raw image file. All of the "raw" images you can actually see have had a significant amount of processing applied to them.
In the case of FRV it's probably extracting the camera generated JPEG preview image attached to the raw file and displaying that. So what you're seeing with FRV is the camera's own processing instructions applied. When you open the same file with LR Classic, it seems to be applying its own default automatic processing routine, including auto white balance and auto brightness adjustment, to the image. You can tell LR to apply a different set of default instructions when it first opens a file. The difference between the two images you're seeing is the difference between one set of processing instructions and a different set of processing instructions for the same data set which, if displayed "unprocessed" would look nothing like what you expect the photo you took.
Most raw image files contain enough data to create a near infinite number of interpretations of that data that will fit in an 8-bit jpeg file.¹ Anytime you open a raw file and look at it on your screen, you are not viewing "THE raw file." You are viewing one among countless possible interpretations of the data in the raw file. The raw data itself contains a single (monochrome) brightness value measured by each photosite (a/k/a sensel or pixel well). With Bayer masked camera sensors (the vast majority of color digital cameras use Bayer filters) each pixel well has a color filter in front of it that is either red, green, or blue.² For a more complete discussion of how we get color information out of the single brightness values measured at each pixel well, please see RAW files store 3 colors per pixel, or only one?
How the image you see on your monitor when you open a raw file will look is determined by how the application you used to open the file chose to interpret the raw data in the file to produce a viewable image. Each application has its own set of default parameters that determine how the raw data is processed. Since each application uses a different set of instructions to process the raw information contained in the file, each result will be different.
One of the most significant parameters is how the white balance that is used to convert the raw data is selected. Most applications have many different sets of parameters that can be selected by the user, who is then free to alter individual settings within the set of instructions used to initially interpret the data in the raw file.
¹ Sure, you could take a picture that contains a single pure color within the entire field of view. But most photos contain a wide variation of hues, tints, and brightness levels.
² Except the "red" filter is really more of a yellow-orange color, the "green" filter is more a yellowish-green color, and the "blue" filter is a violet-tinted blue color. In other words, the colors of the filters in a Bayer mask do not correspond to the three colors our RGB monitors emit and blend to reproduce the response in our retinas that many other colors do. In fact, the colors of the filters in a Bayer mask are much closer to the three colors that each of the three types of cones in our retinas are most sensitive to than they are to the three "primary" colors we use for our RGB color reproduction systems.
