You can't tag your way out of a sales problem

When sales are flat, the first instinct is to rewrite the SEO. Better title, new tags, again. Sometimes it helps. Often it does nothing, because SEO was never the problem.

SEO gets you seen. It doesn't get you chosen.

There are two separate jobs: getting found (SEO) and getting picked (the product and the listing). If you're getting views, SEO is already working, the traffic is arriving. If those views don't convert, the problem is on the page, not in the tags.

Better SEO can make a sales problem worse

If your product blends in, more visibility just means more people finding you and scrolling past faster. You're paying for a bigger audience to reject you. Fix desirability first, then amplify it with SEO.

What to fix before touching your tags again

Whether the product looks distinct from its competitors, whether it's on a rising trend or a saturated one, and whether the listing gives a clear reason to choose it. SEO amplifies whatever's there. Make sure what's there is worth amplifying.