Why is https connection considered insecure in Google Chrome on some sites?

Question

Google Chrome

Chromium has recently been updated to the latest version, and on many sites via https, a notification about an insecure connection appears in the address bar. It is noteworthy that there is a notification on Upwork and Payoneer, but not here on Toaster, Vkontakte and other Russian sites. This aroused my suspicions and therefore I installed Google Chrome not from the repository, but from the link from the main Google - all the same, the connection remained unsafe. While through Firefox everything is fine. OS - Linux Mint 17.1. Do you have a similar phenomenon? Could I have been hacked? What can you do to protect yourself from data theft?

Answer 1

Because there is no certificate.
If I'm not mistaken, green is all protected.
Gray means that there are scripts from other sources.
Well, red is not a certificate.