I've been thinking about signing up for the cloud service. This concerns me because there are no log files like that on my Linux machine or on my Windows machine. I have my database synchronizing with OneDrive.
Yes there are repeated messages, but I don’t really see an error, just a verbose output of synchronisation. For each of them, there is a big block written by <date>: Synchronizer: "Sync target local info:", "{"version_":3,… that is repeated twice.
I’m confident debugging was not enabled, and there is no trace of a flags.txt file on 3 linux machines for which I can see this big log files.
The huge logs aren't normal though. They are usually sized in kilobytes, not in hundreds of megabytes. If Joplin generates such huge logs, then there must be something wrong going on, either in the application itself or the installed plugins.
Indeed it's not normal and it would be good to check the logs and find out what statements often come back. It's probably not sync unless you have debug mode enabled (but you said you don't). Probably a plugin and it would be nice to know which one
I think it's the combination of the OCR process and synchronisation that's causing so many log statements. OCR changes things, and that's uploaded soon after by the sync process.
That will be slightly improve in future versions since now we'll only log an abbreviated version of the sync target info, and also in your case once OCR has completed it should go back to normal.