Unlike Gnome, KDE do actually care about their users, not just about themselves.

It's hilarious how, despite KDE apps being broken on every DE that isn't plasma, people will still find a way to blame Gnome for it.

Contrarily to KDE, Gnome has managed to make sure that libadwaita apps look and work just like they're supposed to and how its shown on the screenshot in the app store. You might not like the theme, but at least you knew what to expect before downloading, whatever distro you are on.

It's great that KDE finally managed to fix their app so that they come with everything it need to function properly. People might be able to use them now on other DEs.

As other have pointed out, saying that "no dependencies are shared" is a very missinformed take, given that sharing dependencies as runtimes is an integral part of Flatpak's structure. But what makes it even funnier and more obvious that you don't know what your talking about, is that you than cite Nix as something you "vastly prefer" when Nix actually deals with dependencies in a very similar way to Flatpak. From the official site:

You can have multiple versions or variants of a package installed at the same time. This is especially important when different applications have dependencies on different versions of the same package — it prevents the “DLL hell”.

In both Flatpak and Nix, apps will only download a different version of a dependency when they need it. This ensure that, instead of breaking, the app will work the same on any system (be it an old stable Debian or a bleeding edge Arch system), without requiring devs to create monkey patches that they have to maintain as things evolve. It has the potential to immensely reduce the burden on app devs and maintainers, and make it a lot easier to make apps for Linux.

Man what a braindead take.

Firstly, you're not adressing the fact that your BS Ad hominem didn't even make sense. You're calling OP a "kids who grew up with “app stores”" when they are talking about prefering to get a .tar over appimages. You're now even doubling down with "That “terminal” app is scary!". I know having actual arguments is hard, but maybe just think for a second before writing something, particularly if you're so desperately trying to be snarky.

Secondly having to using the terminal is fine for experienced user who like the efficiency of it and makes sense for more advanced cli apps or development tools, but for app that are meant for an average it's just a needlessly shitty experience. Same goes for having to look up the website to download a random package from the internet that you're going to run uncontained on your system. Given how easy it is to game the SEO to land at the top, this is just begging for a virus and is an absolutely garbage system.

And it really doesn't need to be this way given that we already have better working alternatives.