The registration script fails (almost) silently on Oracle Linux systems due to rhn-client-tools obsoleting subscription-manager.
The installation runs fine, but the upgrade of subman runs silently without any giveaway when anything goes wrong.
Furthermore, the --setopt=obsoletes=0 flag is not set for the upgrade task, which ends up in rhn-client-tools obsoleting the subscription-manager.
The whole registration process ends with:

'/etc/rhsm/rhsm.conf' not found, cannot configure subscription-manager

Output of yum history with the transactions from the registration:

Transaction ID : 6
Begin time     : Mon Aug 19 08:48:20 2024
Begin rpmdb    : 310:bd639b375359c110c0024dc04a9767557fab6f22
End time       :            08:48:21 2024 (1 seconds)
End rpmdb      : 310:65ca7ef7823d212c243f6b7c6eb930a4e10b5303
User           : root <root>
Return-Code    : Success
Command Line   : upgrade -y subscription-manager
Transaction performed with:
    Installed     rpm-4.11.3-48.el7_9.x86_64                  @OL7LATEST/7.9
    Installed     subscription-manager-1.24.54-1.el7_9.x86_64 @client-tools-for-rhel-7-server-rpms
    Installed     yum-3.4.3-168.0.3.el7.noarch                @OL7LATEST/7.9
Packages Altered:
    Obsoleting rhn-client-tools-2.0.2-24.0.11.el7.x86_64   @ol7_latest
    Obsoleted  subscription-manager-1.24.54-1.el7_9.x86_64 @client-tools-for-rhel-7-server-rpms
-------------------------------------------------------------------------------
Transaction ID : 5
Begin time     : Mon Aug 19 08:48:18 2024
Begin rpmdb    : 307:3404343b66e2a3decadce4a9a80bbc60361f83a1
End time       :            08:48:19 2024 (1 seconds)
End rpmdb      : 310:bd639b375359c110c0024dc04a9767557fab6f22
User           : root <root>
Return-Code    : Success
Command Line   : install -y --setopt=obsoletes=0 subscription-manager
Transaction performed with:
    Installed     rpm-4.11.3-48.el7_9.x86_64   @OL7LATEST/7.9
    Installed     yum-3.4.3-168.0.3.el7.noarch @OL7LATEST/7.9
Packages Altered:
    Install     subscription-manager-1.24.54-1.el7_9.x86_64                   @client-tools-for-rhel-7-server-rpms
    Dep-Install subscription-manager-rhsm-1.24.54-1.el7_9.x86_64              @client-tools-for-rhel-7-server-rpms
    Dep-Install subscription-manager-rhsm-certificates-1.24.54-1.el7_9.x86_64 @client-tools-for-rhel-7-server-rpms