I have configurad journald with following conf,

[test@mcmillan ~]# cat /etc/systemd/journald.conf
[Journal]
Storage=persistent
Compress=True
RateLimitInterval=1s
RateLimitBurst=10000
SyncIntervalSec=1s
SystemMaxUse=20g
SystemKeepFree=20%
SystemMaxFileSize=10M
ForwardToSyslog=no
ForwardToKMsg=no
ForwardToConsole=no

But am getting logs like this from journald

Permanent journal is using 340.2M (max allowed 4.0G, trying to leave 4.0G free of 137.2G available → current limit 4.0G).

Where is this 4 GB coming from which the system is trying to keep free?