Hi Peter,
I’ve read your posts a couple of times …
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Your screen is 100% sRGB capable, which means the display also plays back in AdobeRGB colour space – but only to a certain degree (roughly as far as sRGB is contained) → see graphic
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I do not understand your explanation about “Protect saturated colors” (below your camera’s Color Rendering), while of course OFF with an exported TIFF-file.
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The blueish complementary colour is nothing else than an overexposure warning and the clipping indicates some overload in the red colour channel → too bright.
Similar to when taking a photo from an object with a brigthly lit, predominant colour. -
There also might be oversaturation, but there is neither a gamut warning nor a softproof capability
– if not introduced ‘secretly’. -
Did some experiments with my ColorChecker and adjusted the raw-file’s (black &) white point
with the Tone curve, just shy of the clipping warning.
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Export as 16bit TIFF-file w/ AdobeRGB colour space didn’t show clipping
inspite of the histogram moving slighty when compared to the adjusted raw-file. -
Export as 16bit TIFF-file w/ sRGB colour space showed some clipping (as your example)
and a slightly expanded histogram, ‘touching’ the (black &) white point.
To solve that ‘issue’, I just took down the Tone curve by 1 point (255 → 254).
.
BTW, all exports were done with monitor set to AdobeRGB as well as sRGB colour space
(changed custom profile preset & restarted PL) → no display profiles involved !
note
When exporting a file, at present DxO uses the rendering intent perceptual.
– Say, you have a file in AdobeRGB colour space with some colours, which when exporting to sRGB colour space would land outside the target’s range. The perceptual rendering intent takes care of that and all (not overexposed) colours are moved into the target’s colour range, so that the perception of the present colour renditon is kept. – While simple and userfriendly, all colour values change to some degree, depending on how much ‘outlandish’ has to be stored in.
As already said, with a screen like yours the ‘best’ solution is to export in sRGB colour space
– and even better when your screen is properly set / calibrated.
Should you have a special project, you export as AdobeRGB and reduce to sRGB later.
→ The way back doesn’t work, as you don’t get the ‘extra’ colours back.
And do yourself a favour and try some of the mentioned test pics. 
have fun, Wolfgang
addendum
The above test was done with “Protect saturated colors” ON.
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After digging into that topic (and some understanding), I switched “Protect saturated colors” OFF and repeated the test (5) – but no change w/ the clipping indication, independent if the monitor was set to AdobeRGB or sRGB colour space → no display profiles involved !
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Comparing the histograms of the equivalent output files, I could see the influence of that saturation protection switch, now leading to some ‘sligthly’ higher saturation values in the 3/4 tones (the bright side).