Mobile accessibility required for indexing
Google completed the mobile-first transition: from July 2024 a page must be accessible to a mobile device to be indexed at all.
What changed
Google announced the final step of the mobile-first indexing programme, stating that from 5 July 2024 it would only index pages that could be loaded by a mobile user agent. Sites that served content exclusively to desktop browsers, a very small residual population, risked losing indexing entirely. Google noted that no responsive-design requirement was being imposed and that pages simply had to be reachable and renderable on mobile.
Timing
Rollout began 5 July 2024. No completion date was announced. Rankings typically remain unstable for the whole rollout window, so measurements taken inside it are not a reliable read on the outcome.