IIRC you have to be careful to open the browser, do an immediate restore or lose the option to restore?
Also I'm not sure just how good a restore is, doesn't it reload the pages rather than remembering the state each page was in (e.g. long web page that takes half an hour to read, user is 60% of the way down, doesn't want to lose their progress).
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chrome's bookmark support historically hasn't been as strong as Firefox's IIRC, I migrated to Chrome in the era that FF's multithreading wasn't good then migrated back once it was fixed to get the better bookmark system. Given how these days software makers copy the crap out of each other, it wouldn't surprise me if FF's bookmarking system has been nerfed to make it look/work more like Chrome.