You find the following line in your messages file

 imjournal: filecreatemode is not set, using default 0644

This is not a critical error. To eliminate this message edit /etc/rsyslog.conf and find the line

module(load="imjournal" fileCreateMode="644" StateFile="imjournal.state") 

note it might be written as:

module(load="imjournal"  # provides access to the systemd journal
StateFile="imjournal.state") # File to store the position in the journal

Change the line with

module(load="imjournal" 

to read

module(load="imjournal" fileCreateMode="644"   (if there was other text here leave it here)

then

sudo systemctl restart rsyslog.service

References:

https://www.rsyslog.com/doc/master/configuration/action/rsconf1_filecreatemode.html