In July 2018 Google Chrome is changing the address bar to display “Not Secure” for pages that are running on HTTP:

Who is affected?

This change does not affect the self service portal and the New MapBrowser. 

Our Class MapBrowser runs on HTTP and as such is subject to this user interface change. The only difference is the visual indicator of "Not Secure" in the URL bar, the underlying security of MapBrowser has not changed. 

Are Nearmap users’ usernames and passwords secure?

Yes. The login process happens over HTTPS, thus the credentials are protected, following username and password best practices.

More information from Google: