Effective July 2018, the Google Chrome browser marked non-HTTPS sites as ‘not secure’
Google has been pushing webmasters to change websites to HTTPS for years now. They even gave a small rankings boost to HTTPS sites.
February 2018 Google published this announcement:
“For the past several years, we’ve moved toward a more secure web by strongly advocating that sites adopt HTTPS encryption. And within the last year, we’ve also helped users understand that HTTP sites are not secure by gradually marking a larger subset of HTTP pages as ‘not secure’.
Beginning in July 2018 with the release of Chrome 68, Google Chrome started marking all HTTP sites as ‘not secure’“.
If your website is still HTTP, then go to Free HTTPS to fix it.