Based on the related forum post by @Robert-MX, I was able to resolve the "file '/var/log/syslog'[7] write error - see https://www.rsyslog.com/s>" spamming the journalctl logs after a reboot due to the logs not being cleared properly.
The root issue appears to be that /usr/lib/armbian/armbian-truncate-logs has an issue when ran with as #!/bin/sh after a reboot. To get around that it manually with bash instead.
To fix it temporarily until the next reboot then just run
sudo bash /usr/lib/armbian/armbian-truncate-logs
check 'journalctl -f' to see if the rsyslog issues disappear, if so then you'll want to add it to your crontab for every boot
To fix it permanently then add the command to your crontab so it runs every time you boot:
switch to root
su -
edit your crontab
crontab -e
add the line at the bottom so that the log truncate happens after each boot
@reboot bash /usr/lib/armbian/armbian-truncate-logs
reboot and check journalctl -f to see if you are still seeing the rsyslog issues