Google released its September 2026 spam update on 24 September, for all countries and all languages, and said it could take up to two weeks. Google confirmed the rollout finished on 8 October. Google hasn't said what this update targeted.
Google's spam policies cover things like pages churned out at scale with no value, bought links and pages built only to rank. Most Shopify brands have nothing to fear. The brands at risk bought cheap links, or pumped out hundreds of thin blog posts or near-identical collection pages to chase keywords.
If your organic traffic fell in that window, don't panic-edit the whole site. Find the pages that dropped, check them honestly against Google's spam policies, and fix or remove anything that doesn't help a shopper.