I am new to the Opera browser. I've been using it for about a week. What's App and Facebook Messenger keep auto activating. I don't have accounts with these services.
Judging by how long this seems to have been a problem, and Opera's lack of response, I assume Opera is being paid to subtly promote the services. Which really sucks. I'm going to keep looking into it. If Opera is doing that though I'll go back to Firefox as fast as I can hit the uninstall button.