Well It seems that the problem is with one of the color balance modules I use.
It creates a vignette, darkening midtones, lights and shadows.
It applies an elliptical mask and uses a parametric luminosity mask in order to preserve the extreme lights and shadows.
If disabled the module, the photo is exported OK.
If I disable the masks of these module, the export is correct too.
The problem seems to be with the parametric mask, when this is enabled the export is not correct.
If I deactivate the ellipse mask and leave only the parametric mask, I can see artifacts en the screen too:
But if I activate parametric and ellipse mask, in the screen it looks OK, but not in the export.
I provide the raw file and the xmp.
If somebody can do tests with the image it would be greatly wellcome.
IMG_8110.CR2.xmp (39.4 KB) IMG_8110.CR2 (28.6 MB)
It seems a bug with the creation of the parametric mask in this particular image.