Google started its mobile-first search indexing over a year ago, and now it’s ready to make that approach the law of the land. As of July 1st, 2019, Google will index the phone-oriented sites by default for any new web domain it registers. If you’re starting a new site, you’ll want to be sure its mobile version is polished and full-featured — that’s the version Google will use to parse the site’s structure and extract useful snippets.
Google makes mobile-first search indexing the default for new domains – Engadget
