I started a kit Viognier about 3 months ago and put in yeast nutrient,
not realizing it's been added to the kit. The wine developed an off
smell in the end of fermentation - somewhat putrid is the closest
description. It didn't smell like hydrogen sulphide, but I've treated
it with copper sulfate anw and clarified after. It's been bulk aging
since then, the smell is reduced but clearly noticeable in the glass
and first 2-3 seconds the wine is in the mouth. The taste is
distinctly salty and a "oily", covering the fruit.\

The wine was on lees for about 3-4 weeks total.

Any ideas what went wrong - was it the yeast nutrient? And more
importantly, can I still save it somehow?

Any help appreciated,thx,

Pp