Reproduced. Would you mind reporting this formally as a bug at https://github.com/nextcloud/bookmarks/issues?
Can anybody tell me what to do or at least where those settings are taken (database or file)?
As a temporary workaround, you can toggle the value in a particular account via occ user:setting for the bookmarks app in the same way as described here for a different setting in the photos app: Issue with Photos Plugin and Samba Mount in NextCloud - #10 by jtr