My experience with both Opera and Opera GX have been terrible. For me that I have dozens of folders and hundreds of sites in the favorites was a nightmare! This is a problem that must be solved absolutely, if a similar situation should happen to me again, I will stop using Opera browser. So you have to move all the folders manually and if you don't drag it correctly into the subfolder, you can't move it anymore! Then you have to recreate another folder and manually transfer all the sites that were contained before. To transfer and arrange the favorites on a new notebook it took me 3/4 hours! I have tried both exporting / importing via HTML files and synchronizing between two computers but the problem is the same: the favorites in the folders in the 'Quick Access' screen are not transferred to the Browser screen but remain in the path of the folders of the bookmarks in the sidebar. I have been using Opera for over 15 years and it has always been my favorite browser, but after the experience of the last couple of days I am quite sorry.

Opera browser review