I can’t find any options to change verbosity level and I question the necessity of the high default Joplin is set to. This is junk data for most users and looking at my own log it seems to have no purge limit either, having just exceeded 1M lines.
Not a big deal perhaps, but not really regular practice nor useful.
Log level is not verbose by default but it’s possible that some log statements should not there. I guess all the reducer actions in particular could be removed.
Inspecting my log closer, the most common entry is "ExternalEditWatcher: Stopped watching all files" but the message is repeated between 80-120 times per second according to the timestamp. These entries stops repeating in late November though, but the same repeating behaviour still persists with "Scheduling sync operation...". Last seen 2019-02-17. (I updated to the latest version very recently)
My sync-settings are set to 1 hour.