S-Log3, as does S-Log2, needs to exposed correctly in camera, otherwise the colors fall apart. I've shot very dark low light scenes with the F55 and FS7 and both times I over exposed by two stops or more with S-Log3, to keep the waveform above 20-30IRE. The reason is that the sensor is rated for 2000ISO, but's "actually" a 500 ISO rating. The sensor has it's best performance at a 2000ISO rating, but it's an experience of mine that anything under 20-30 IRE is broken in terms of noise and color. Noise affects color, as it's not just a little luma noise as with other cameras, but a rather heavy chrome noise. When I talk about the IRE, I'm referencing the LOG-Gamma, not the translated Image to Rec709. So a S-Log3 Image, and it's entire spectrum on the waveform being between 50-10, would be massively underexposed and therefor the skin tones would also be damaged.
I've graded a lot of S-Log material and this has been my personal findings. That whenever it's "properly" exposed, as in above 20-30IRE, the material holds well, whereas if it's exposed at base ISO, the material tends to break apart if the image is at the lower end. Especially in high speed footage.