2020-03-06, 05:24 AM
According to Google
Quote:we'll be switching to mobile-first indexing for all websites starting September 2020. In the meantime, we'll continue moving sites to mobile-first indexing when our systems recognize that they're ready.
Quote:While we continue to support various ways of making mobile websites, we recommend responsive web design for new websites. We suggest not using separate mobile URLs (often called "m-dot") because of issues and confusion we've seen over the years, both from search engines and users.