Both clips were shot at base ISO 640. The internal codec was XAVC S-I S-Log3/S-Gamut3, the external was ProRes RAW HQ via the Atomos Ninja V which was then transcoded to ProRes 4444 in Apple Compressor. Sony a7s III in-camera noise processing is splotchy and enlargement reveals unsightly banding artifacts, whereas the externally recorded footage suffers from chroma noise which is easily mitigated with a tiny amount of noise reduction in DaVinci Resolve Studio. Transitions between tones in the 12-bit footage are smooth. A few observations: (1) you don’t want to add noise reduction in post on top of footage that’s already been de-noised in-camera; (2) shooting at base ISO, exposing to the right (ETTR) and pulling shadows down in post can help reduce the amount of noise, but as we can see, it does nothing to eliminate banding in the XAVC S-I footage; (3) it’s advisable to use the least amount of noise reduction in post as possible, as excessive noise reduction will destroy fine detail and texture. Our recommendation is to avoid Sony’s internal codec. Noise reduction settings for the ProRes 4444 clip: Temporal – Faster – Medium -Luma 2 – Chroma 2. Both images enlarged 999%.
And here’s the same ProRes 4444 clip with a small amount of spatial noise reduction added on top of the temporal NR. Settings: mode faster – radius small – Luma 2 – Chroma 2.
If you begin to see distinct features, dial back on noise reduction.
Settings: Temporal – Faster – Medium -Luma 2 – Chroma 2.
Spatial – Mode Faster – Radius small – Luma 7 – Chroma 7.
Spatial – Mode Faster – Radius small – Luma 7 – Chroma 7. We can see ugly stepping.
The Daejeon Chronicles 
I’ve been testing RAW to Atomos from my Sony A1. The Raw output has unfixable purple false colour appearing on fine edges – for example lines on a barcode. I don’t know if the A7Siii has this issue? So I gave up with RAW unfortunately.
That’s the first time I’ve heard of that issue. The a7s III does not have any such artifacts.
So unfortunately as the Sony A1 has line skipped 4.3k RAW output, it is clearly screwing up the image and this is revealed in the RAW stream devoid of internal processing. Definitely cannot recommend the A1 for RAW video. However, the 8k native recorded to Atomos 4k (which creates an oversampled stream) provides a stunning Log image.