That’s it, Wolfgang
In simple terms, the reason for the difference in the exported JPG (in this one particular case) is because; [“Same as Soft Proofing” AND Soft Proofing deactivated ] is effectively equivalent to “As Shot”
That’s why my image was producing “unexpected” export results - 'cos it came from a camera with Color Space = AdobeRBG …
- which is ironic - 'cos I have warned elsewhere about the potential “gotcha” in using the “As Shot” option - for exactly this reason … not realising I was doing precisely that myself, by default !!!
John