I am not certain what in the two RAW corner samples you want to draw my attention to. Is it the horizontal intensity gradient, the fine border (your Fig 2 does have a fine border too, but hard to see because it's brighter)? One has to keep in mind that distcorr also affects RAWs (and LIVEVIEW). Can you please be more specific ?
You said earlier .....
Do not use native RAW or JPG, as both are corrected.
Note quite. I can use native CR2s! Yes, the JPGs are corrected, but the CR2s are not. I discovered this and made a big deal somewhere in this thread. They appear correct in Canon PC software because it detects their own RAW files and applies the *same algorithms* that are in the camera for correcting JPGs, in PC software for displaying the native RAWs. But if you look at a CR2 with Rawtherapee, it is uncorrected !!! That's what we want on this side of the planet.
WRT the borders .....
Now I have some answers. In general, this is what I see on the 100c with lens. Firstly, this border is problematic because it appears in both DNGs and CR2s. I see it on the 101c instrument camera too. As such, it will give stitching issues in instrument mosaics if not suppressed (but suppressing this may not be possible unless it's directly related to vignetting). At full wide the DNG border is 2X thicker than the CR2, but the left side has no border. The CR2 is 1/2 thickness with a border around the whole image.
CR2s -- 10 zoom levels 3676x2752, thin border around whole image
Zoom 0 to 7: visible border
Zoom 8 & 9: no visible border
All images same size.
DNGs -- 10 zoom levels 3668x2760, thick border, top, right, and bottom
Zoom 0 to 3: visible border
Zoom 4: faint border
Zoom 5-7: very faint border, needs TC+ to see
Zoom 8 & 9: no visible border
The extra bit of info ... a CR2 is 3676x2752, but the JPG 3648x2736 (looks like the JPG is smaller by the thickness of the border), and the interesting thing is that the two sizes stay the same for all zooms I tested. I think the border is there all way through -- it just gets more faint. It's possible this is related to vignetting but I can't see how.