i found the original in reddit, from about four years ago

https://www.reddit.com/r/kde/comments/tffr4l/some_kde_plasma_uiux_problems/#lightbox

(i'm not saying it's related, but at least people should be able to read the text now)

GNOME: Designers trying to Develop a desktop. KDE: Developers trying to Design a desktop.

Honestly I just want KDE to do the backbone and GNOME to do the designs.

Adwaita apps look just right, minimalistic yet powerful, pinnacle of modern simplified designs. Everything you actually need is close, and the rest doesn't clog the view.

The rest of GNOME is heavily meh. Customization is next to nothing, and generally any workflow falling outside the one window = one task paradigm is gonna be a pain. Settings are convoluted and sometimes straight up unreachable without additional tools or config edits (and sometimes they don't even apply).

I guess what unites Adwaita and GNOME project overall is the stubborn adversity to users making it comfy for themselves - it's the GNOME way, or no way. And while Adwaita is at least actually good in its defaults, GNOME is not.

KDE, on the other hand, is brilliant as a desktop environment, but menus could be so, so much better. So, when I have a choice, I use Adwaita-themed apps on KDE. With proper theming on KDE side of things, they come together just right.

Looks much better to me nowadays, although yes, I am not using the default Breeze theme. But if there are any problems in the theme I am using, they are much more likely to not be present in Breeze.
Some "issues" pointed out in the picture are not issues at all.
The "Different font styles and sizes" for example, because they are used for different things with different scopes and user interaction.

All of that and it's still nicer to look at for me haha.

I feel it has gotten much better in recent years. The first time I tried KDE 5 it looked weird to me. But now I acutally quite like KDE 6. Or maybe I've just learned to tolerate it...

Pixel perfect doesn't mean that things will feel aligned. This is a very naive vision of UI design. I'm not saying that things can't be improved but this is not a valid point

Oh for fuck’s sake…

Actually, I don’t. What am I looking at?

Kde has mostly small padding and alignment issues instead of having a completely random design.
I can live with that.

I have a theory that if everything was pixel perfect, centered, perfectly aligned and looked the same, the thing would look too sterile. There's basically a perfect world, written down in books and texts that is being taught to students and there's the real world. In many areas, these two do not match and the above image is the result of someone's text book world view not matching the real world.

Could the discover store have a better UI? Yes. Will a centered, down-anchored, pixel perfect button make it better? Subjective.