Is that Workaround for KDE (xdg-desktop-portal-gnome) needed for all of us?
Cause I don’t experience any lagging when starting programs.
Even Brave browser and Libre Office start as quick as always.
Was it fixed in the meanwhile, or shall I still install that fix?
sudo pacman -Rdd xdg-desktop-portal-gnome
sudo pacman -S xdg-desktop-portal-kde
I myself don’t even have xdg-desktop-portal-gnome or xdg-desktop-portal-gtk installed.
I’m running Plasma, and the only two I have installed are the generic xdg-desktop-portal and xdg-desktop-portal-kde. If you’re running Plasma, then you don’t need any of the others.
Edit: package names corrected.
That is strange, cause I have neither of the two
xdg-portal-desktop
xdg-portal-desktop-kde
installed.
Is there any action needed on my side?
Well, it depends on your preferences. If you like the one with the GTK look, then you can keep it. Personally, I prefer the KDE/Plasma look & feel, and I prefer consistency across my desktop.
Do I understand it right, that those two
xdg-portal-desktop
xdg-portal-desktop-kde
are needed for a consistency KDE/Plasma look & feel across my desktop?
I would prefer that as well, so than I would have to install it?
Only the second one, normally — the description of the first one states that it’s needed for sandboxed applications (which I don’t have), but I found that removing it caused a problem with the second one, and that reinstalling the first one solved that.
I just searched for
xdg-portal-desktop-kde
but nothing comes up in Pacman GUI.
From where did you get it than?
Edit:
Oh my goodness, I copied and paste it, which doesn’t bring a result!
When I search
xdg portal desktop kde
than the search works!
Strange !!
I think you mean the Pamac GUI. pacman doesn’t have a GUI. 
Maybe you need to refresh your mirrors first. It’s in the normal Extra repository, and if you’re on Plasma, then it should come installed by default.
Yes, of course, I’ve got both installed, just the search by copy and paste messed it up.
Thank you for the explanation !!
Pedant point: even if you don’t have the GNOME and GTK ones installed, Gimp will still use its own built-in GTK file chooser. 
Now, I understand the background a little better and why I didn’t experience any lagging, cause I have only those two
xdg-portal-desktop
xdg-portal-desktop-kde
installed and none of GNOME and GTK !!
Thanks again.
However the search in *Pamac GUI" confused me!
Why copy and paste doesn’t work?
I checked it several times!
Try copy and paste that
xdg-portal-desktop-kde
no result !!
We doesn’t know, Preciousss. We doesn’t uses the Pamac GUI. It doesn’t tastes deliciousss.
For quickly looking up on a package, I generally use Octopi, but for installing and/or removing packages, I use pacman, and for AUR packages, I’ll normally use the command-line version of pamac.
It’s listed as xdg-desktop-portal and xdg-desktop-portal-kde in Pamac.
Notice that you inadvertently changed the package names. They are xdg-desktop-portal…
Um, color me dense — I know there’s a humorous reference in there, but I can’t see it. 
Sorry, it wasn’t a joke. You switched the words portal and desktop between them.
Edit: Fixed typo
Apologies, my bad.
Must be the heatwave.
No problem, I think there were a little bit of misunderstanding because of it. Just that.
Yes, because it is/was wrongly in the update announcement and I just copied it and no doubt it’s hot outside.
What? No you need both … the desktop-specific ones are backends for the ‘regular’.
Installation
Install xdg-desktop-portal and one or more backends.