Tested it and everything worked as expected.
It was in testing for 15 days. Isn't is supposed to be in EPEL already automagically after 14 days?
Thanks! I just gave it a quick test and works for me. I found just one minor problem: geoip is completely disabled. The geopip2 driver of syslog-ng uses libmaxminddb, which is available in RHEL8.
Fixes the problem I originally reported at syslog-ng upstream: https://github.com/balabit/syslog-ng/issues/2377
Tested the syslog-ng part and it works now fine.