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I did as recommended. Thanks!

I just pressed the sync button. I was able to figure out what the problem is. It was a bug. Angry bug. My 20 bookmarks were cloned at about 37000. I think this happened when I clicked "merge information on pc and server". For some reason, even the same bookmarks were simply cloned and this happened for a long time. Now deleted bookmarks. Synchronization OK.

The Chrome extension is CPU intensive. The syncing of bookmarks does not end.