I've installed a fresh Jenkins jenkins-2.401.2-1.1.noarch.rpm on an empty RH8
server.

The server starts fine and when I connect with the browser to port 8080,
I'm asked for a first administrator password from the file
/var/lib/jenkins/secrets/initialAdminPassword
When I provide it, the page in the browser only presents some ongoing
pattern, three small vertical bars which are moving up and down, but
nothing more.

The last line in /var/log/jenkins/jenkis.log says:

74565d94443f4ed08790bf86da7953fd

This may also be found at: /var/lib/jenkins/secrets/initialAdminPassword

*************************************************************
*************************************************************
*************************************************************

2023-07-24 11:45:26.217+0000 [id=34]    INFO    jenkins.InitReactorRunner$1#onAttained: Completed initialization
2023-07-24 11:45:26.228+0000 [id=25]    INFO    hudson.lifecycle.Lifecycle#onReady: Jenkins is fully up and running