One of those inexplicable questions is that that RH-RHEL is based on various Fedora spins fixed in time. OK. But Fedora has a KDE Spin. RH use to support both GNOME AND KDE before they decided to stick with ONLY GNOME. openSUSE and many other distros have both a GNOME as well as a KDE offering… other than – of course – Red Hat. Given that RHEL is based upon some version/s of Fedora, and that Red Hat once supported both GNOME and KDE for years and years, now makes no sense. It is the finger in the eye. Yeah, I get it: RHEL is suppose to be ONLY for servers, which IMHO is a gigantic mistake. Beyond “Servers” there are a lot – an understatement if there were any – of people who run WORKSTATIONS. A business – any business – succeeds or fails based on good customer relations as well as good word of mouth. Within the past 2 years Red Hat screwed over the CentOS Community, a very vibrant community; second they decided to no longer support KDE. That Red Hat is creating a lot of ill will with its actions as of late can’t be understated. If Red Hat pisses too many people off, it would not be inconceivable that someone might fork Red Hat’s code.
I’m still waiting for Red Hat to issue a new kernel to supersede kernel 9.1 which came out over a month ago and is buggy as it goes. Maybe Red Hat is throwing all its eggs into the RHEL 9.0 basket and ignoring RHEL 8.x. The problem with that strategy is that any XYX.0 release is is filled with bugs, and is seldom ready for Prime Time before the XYZ.2 or .3 release comes out – that’s 1-2 YEARS down the road.
As to KDE… I have a Love/Hate relationship with KDE 5. Someone should have put KDE 5 out of misery a long time ago – someone should have stuck a fork into it a long time ago – it is DONE!! But still it drags on now at version 5.26 (!!) KDE 4 was killed off at 4.14, and it was a superior DE in many ways to KDE 5, and far less buggy. KDE 5 is the Zombie DE that refuses to die!!
As to your problem with KDE Plasma not working as expected part of the problem is induced by Red Hat, and Part by KDE. KDE works fine in openSUSE 15.3 Leap which makes me think that part of the problem is induced by Red Hat; that said KDE 5 manages to screw up lots of things – in one version XYZ works fine, but then they introduce new code that breaks XYZ, then they fix XYZ, but that breaks ABC, and so on and so forth; now throw Red Hat into the mix and… you get the drift.
The best way to solve the problem is to give Red Hat the finger and ditch SDDM altogether, as well as GDM. Install LightDM. Back in CentOS 7.x GDM lead to run away processes, so I installed SDDM to get around the GDM problem. On the very next point release Red Hat managed to royally screw up SDDM as well. Once again i was forced to find an alternative, and I stumbled upon LightDM. Highly configurable and it should fix most of your problems. I have it installed on my Workstation running Rocky Linux 8.5, with a KDE DE. I can’t say if it will work in 8.6, as 8.6 blew up my system and I had to roll back to 8.5.
If you are running Nvidia under 8.6 that is so far a no go, but it works fine under 8.5. There is something really screwed up in RHEL 8.6 (and its children). I can only hope that Red Hat is going to release a new kernel very shortly has 9.1 is a disaster.
D’ Cat