Google is making a final switch to using mobile browsing as the main way to index websites for search results. This means they will be checking websites with a "smartphone crawler" instead of a desktop computer crawler
Most websites don't need to do anything because Google can already access them with a smartphone crawler. But if your website content can't be reached at all on a mobile device, it won't be included in search results anymore.
After July 5, 2024, Google will only use the mobile crawler for all websites. You might still see mentions of a "desktop crawler" in reports, but that's for other Google features, not search results.