By the time conversion rate visibly drops, a listing has usually already been losing ground for weeks. There are earlier signals worth watching if you want to catch the problem before it shows up in your sales dashboard.
First, check your search term report for a shrinking share of branded versus non-branded traffic. If a growing share of your clicks are coming from your own brand name rather than category keywords, your organic ranking on generic terms is likely slipping. Second, watch your unit session percentage relative to competitors in the same price band; a widening gap is a content or pricing issue, not a traffic issue.
Third, review your most recent negative reviews for recurring themes rather than treating each one as isolated. Patterns in returns or complaints often point directly to a gap between what the listing promises and what the product delivers. Fourth, check whether your main image still meets the current best-practice bar; standards shift every year and an image that looked competitive two years ago often looks dated now.
Finally, look at your A+ Content or Brand Story modules. If they have not been touched since launch, they are very likely stale relative to what your best-performing competitors are running today. None of these signs alone is urgent, but together they are a reliable early warning that a full optimization pass is overdue.