ENVIRONMENT
CENTOS = 7.8

vi /etc/rsyslog.conf

# Load the MySQL Module
module(load="ommysql")
#*.* : ommysql:127.0.0.1,Syslog_Database,syslog_user,password
*.* : ommysql:127.0.0.1,Syslog,rsyslog,MYSQLPASSWORD


$template TmplAuth, "/var/log/%HOSTNAME%/%PROGRAMNAME%.log"
*.* ?TmplAuth




CASE SUMMARY
I have configured centralized log server on centos for my windows servers thru SolarWinds_Event_LogForwarder agent. I am able to forward the logs with hostname under /var/log folder. Everyday I see current day logs and previous day logs disappear.

Perhaps you have a misconfigured logrotate?

I did not configured any log rotate. Its a default file

[root@CentralizedLog /]# vi /etc/logrotate.conf
# see "man logrotate" for details
# rotate log files weekly
weekly

# keep 4 weeks worth of backlogs
rotate 4

# create new (empty) log files after rotating old ones
create

# use date as a suffix of the rotated file
dateext

# uncomment this if you want your log files compressed
#compress

# RPM packages drop log rotation information into this directory
include /etc/logrotate.d

# no packages own wtmp and btmp -- we'll rotate them here
/var/log/wtmp {
monthly
create 0664 root utmp
minsize 1M
rotate 1
}

/var/log/btmp {
missingok
monthly
create 0600 root utmp
rotate 1
}

# system-specific logs may be also be configured here.