@cratte I use several browsers. Opera is currently my default but I was along-time Firefox user. At this point Firefox's auto-complete is still superior to all competitors. It's difficult to explain but basically everyone needs to copy Firefox! It is one of the key features that kept me glued to Firefox for years.
Opera's implementation is not too bad but still not as good as Firefox's. but now the other features of Opera have tipped the balance, hence why Opera is now my default.
Opera Sync has an engine to delete duplicates, but don't know its rules and efficiency.
Try SuperSorter from Chrome Store and take care when deleting, keep a BackUp, even from the messed BK.file.
Windows 7 (x64)
Opera Test profile | Opera Back up | Reset
Thank you. I can't believe I haven't thought of that and it turns out the solution was that easy. It will take me some time to take the bookmarks out of folders they were thrown into, but at least I have them in browser now.
@HS-Devil Turbo is no longer part of Opera.
If you can access the site using the VPN, then it means that the site (or your ISP or government, etc) is blocking your access.
If other browsers can access the site, try using an extension to change the Opera's user agent to see if it helps.