I migrated from S3 storage to a joplin selfhosted server, but I forgot to apply the changes to one of my computers and now I have "divergent" notes. Is there a way to "merge" them without duplicate notes?
Not that I know of. But by sorting notes by "last updated" on your divergent device you can locate the few notes that have changed since the fork. Export only those notes to JEX, import into main device. Use the diff view plugin for easy diff to manually merge your conflicting notes one by one. Good luck.