I closed myself the bug that I reported. NOTABUG.
“KDE Plasma Workspaces” installs just fine on 9.4 (tested on AlmaLinux 9.4 Minimal Install). It only fails to install on 9.3.
The situation is likely due to the fact that there is a unique EPEL9, not EPEL9.3 and EPEL9.4, and the KDE upgrade released after the release of EL9.4 wasn’t supposed to work with EL9.3.
I suppose we tend to forget that we should upgrade to the next point release ASAP.
Which brings me again to the furious rant: why on Earth is EL structured on x.y releases, as long as, without an EUS, the previous x.y release isn’t supported? What I mean is that, to the extent of my very little knowledge, 9.3 is not supported with updates once 9.4 is out, not for a single day, unless one pays for EUS. This is beyond stupid. A continuous upgrade à la Stream makes much more sense.
Furthermore, as long as EPEL is not split into dot releases, i.e. there is EPEL9, but no EPEL9.3, EPEL9.4, etc., it’s bound to break the previous dot-release. So at one moment EPEL is broken because it doesn’t yet have the packages for EL9.4, and the next day it breaks EL9.3 because it has packages built for EL9.4! How are people even using EPEL? In all these years, I never thought of this, but now that I do, I realize how stupid EPEL’s design is.
Even with the changes to be adopted with EL10, EPEL9 and EPEL8 will keep being broken by design.
I seriously consider switching to CentOS Stream 9 and epel9-next, but only with Synergy from AlmaLinux still works with such a setup. Unfortunately, I’m too pissed off to experiment and to replace the OS in my computers, so I’ll probably go on with AlmaLinux 9.4, while cursing the completely retarded idiots who designed the point releases in EL, and the non-point releases in EPEL.