The plasma package kinfocenter is not present in EPEL 10 and cannot be installed and therefore there is no 'About this system' window in plasma settings. It is present in EPEL 9 and the Fedora repos.
Closing as I think this is the wrong place. I've added an issue to the KDE sig.
https://pagure.io/fedora-kde/SIG/issue/613
Metadata Update from @alaurie: - Issue close_status updated to: Duplicate - Issue status updated to: Closed (was: Open)
This issue has been migrated to Fedora Forge: https://forge.fedoraproject.org/epel/steering/issues/314
Please continue any further discussion there.