Therefore, I did some digging, and ended up going to opera sync - where indeed i could see that my Bookmarks numbered 777, across about 7 devices that i had used in the past (which i now do not have).

I was using ChatGPT to get me to this point and it told me that i should click Passphrase reset in order to have these bookmarks showing. Normally, a reset as i know means the data will be gone, but i did not think much of this because i.e. - "Do not remember your key synchronization password (passphrase)? Reset Passphrase" - makes it sound like i am only resetting my password without necessarily losing anything - just like a password reset for my email if i forget it right??

I signed out of Opera after this but low and behold, when i signed back in, i can only see about 80 bookmarks (down form 777) and 1 synced device (which is my macbook - down from 7 devices).

I inquired further from ChatGPT and Gemini and there was some suggestion to copy paste my bookmarks 'path' blah blah ..It said this:
Step 1
1.Open Opera on your Mac.
2. In the very top menu bar, click Opera > About Opera (or type opera://about in the address bar).
3. Scroll down until you see the section labeled Paths.
4. Look for the Profile path. It will look something like: /Users/yourname/Library/Application Support/com.operasoftware.Opera
5. Highlight and copy that entire file path.

Step 2:

1. Open that hidden folder on your Mac
   2.Click on an empty space on your Mac desktop to bring up the Finder.
2. In the top Mac menu, click Go > Go to Folder... (or press Cmd + Shift + G).
3. Paste the path you copied and hit Enter.

Step 3: Look for Backup Files

1. Inside this folder, Opera keeps local copies of your bookmarks.
   Look for files named exactly like this:
   -Bookmarks
   -Bookmarks.bak (This is your holy grail right now—it's the automatic backup)
   ETC.....

However, i do not ant to do any potential further damage and would therefore ask here if there is a way i can rescue these bookmarks, devices having the bookmarks. @leocg

Cheers