I've seen the same thing and in the last few updates there's been no fix which means they are probably unaware of it or it is a Linux only issue.

Ok, maybe I have ocd or I'm just seriously picky but I need certain extensions to be first/second/third. I was a die hard opera users for years but the Linux version was recently released.

My other issue is that I only have a few preselected search engines that can be made default. I need my Duckduckgo or Startpage to be default. I've setup hotkeys but I often forget

I've always had reservations using Chrome/Chromium because of all the Google remote connections and WebRequest API crud beyond most users knowledge.

After looking at all net activity I've only been able to identify a few opera services.

sitecheck2.opera.com
addons.opera.com
updates.opera.com

The sitecheck host is a malware domain checker that uses http instead of https but it has no option to disable.
The others are understandable if you want updates or to install/update an extension.

It's great to have a webkit/blink opera browser(especially for me in Linux) that isn't heavily leaking out my personal data. I'll keep monitoring tcp/udp connections just in case but I've already made the opera-developer version my default browser.