Posting about your problem
After have done the steps above and confirmed that the problem is most probably in Opera, it's time to post about it.
Start the topic with a title that briefly describe the problem so people will know about what this is about.
Don't try to explain all the problem in the title but also try to not make it too generic.
Use tags to make it easy for other users to find posts about similar issues. If posting about Opera Mail then add the 'Opera Mail' tag
In the post (body) you should include the following information:
Your OS (Linux, Mac, Windows)
Your version of Opera GX
If the problem is with a page, a link to it
A screen-shot of the problem if it's related to something not showing as should
A description of the problem, including as much as information as possible
Steps to (try to) reproduce the issue
Expected behavior and actual one
It started happening to me in normal Opera couple of weeks ago - before that messengers stayed disabled all the time and now Facebook keeps popping up every couple of days.
Do you have Opera Sync enabled? I suspect it might be another example of Opera Sync feature being broken for years now. It keeps syncing and undeleting bookmarks, I removed, every now and then.