When you startup Node-RED it displays a lot of great info about the system but it does it with the [info] tag. This is all well and good, but several nodes (the mqtt nodes for example) spit out [info] messages too which clutter up the log.
I'd like to suggest that the startup messages (everything up to and including
...... - [info] Started flows
always show at startup time regardless of the logging level. Then if you choose to set the level higher than [info] you will see the startup messages but not fill the log with other [info] messages.