How to turn "Suppressed n messages from /" into visible, logged messages?

CentOS 7.9, latest kernel, latest micro updates. The console log level is set to "debug" (7) to see all messages I can get. Suddenly:

grep "journal: Suppressed" messages | less

shows messages like

Jul 22 17:35:21  journal: Suppressed 603 messages from /

To make these visible I tried:

# vi /etc/systemd/journald.conf

RateLimitInterval=30s
RateLimitBurst=5000

# systemctl restart systemd-journald
# systemctl daemon-reload

However, then this happens:

Jul 22 18:27:01 .. rsyslogd: imjournal: begin to drop messages due to rate-limiting
Jul 22 18:27:46 .. rsyslogd: imjournal: 651 messages lost due to rate-limiting

etc. I tried to make these visible with

# vi /etc/rsyslog.conf

$imjournalRatelimitInterval 30
$imjournalRatelimitBurst 5000

systemctl restart rsyslog

After the changes, neither the "Suppressed" messages are logged, nor the imjournal messages. Actually, now /var/log/messages looks perfectly alright as if no issues exist on the server. But as the server previously suddenly without obvious reason crashed, I am sure something is wrong. Why is nothing logged? The intention was to find out what is causing these "/" sourced "messages", what are these and how can I see what should actually be reported?