Using PatDavid’s skin tone matching technique using the color of the two passe-partout:
Other cameras would have put their “computed” color temperature in the Exif (unfortunately not the case here), so you could use that as a starting point in Colors > Color temperature, the other slider being either eyeballed, or set to some estimate of the actual color temperature of the light source.
Btw, there is a slight reddish cast at the bottom of the passe-partout, also visible in the "good " one.