From an SEO auditor's perspective, ranking drops usually come from a mix of updates and technical issues rather than a single cause. Common culprits include Google core updates, shifts in ranking signals, indexing problems (crawl errors, robots.txt restrictions, noindex mistakes), canonical or internal linking changes, page experience signals, and content misalignment with current intent. To diagnose, start with Google Search Console: compare coverage reports and performance before/after, inspect individual URLs with the URL Inspection tool, and check for manual actions. Then run a quick technical audit: verify sitemap accuracy, robots.txt, 301s/redirect chains, server errors, crawl budget signals, and site speed/mobile usability. Also review backlink profile for unusual shifts and re-evaluate on-page content against user intent and E-A-T signals.