I had also problems with the loin cloth in Cycles.
Cycles have problems with (to) low poly models.
Not sure if you have the same problem, but see Is there a workaround for the terminator problem?
Even rendering in Eevee, loin cloth is not same as visible in material viewport.
i read somewhere, like reversing the face in UV map in Edit mode…but could not apprehend.
Did you normalize faces outwards?
Did you apply the scale?
Did you apply modifiers?
Best is make a temporary copy, before starting to apply changes.