The tree widgets on the left are mismatched: some solid lines, some spaces with alphanumeric characters; the alpha characters are black, yet the lines are gray visual noise that creates visual processing and cognitive load for no reason, adding nothing.
The parenthetical text at the top has a title whose margin (left whitespace to other widgets) is significantly different from the text below it; there are spaces between the parentheses and the text, which no text or print style guide in the world endorses because it separates the parenthetical indicators from the parenthetical text, when they should be tightly bound for clarity.
The window title preserves the absurd convention of using both the binary name and a descriptive title together, and separates them with a typographical element (an em-dash) which is inappropriate in a label or design element because it is asynchronous—it indicates a delay in interpretation and pronunciation (as the em-dash just a few words ago in this paragraph does) and thus suggests long-form reading, which is not the intent for at-a-glance window titles (unless you don't want them to be very usable).
The title of the list widget, "Information Modules" is superfluous and redundant; the user starting an "About" dialogue expects to see "information" from the start, and they do not need to know about implementation ("modules").
The resize handle contrasts significantly with the window background, drawing undue attention to this particular area of the window above others (why is it "louder" than the window title, for example? Window controls should be secondary to window content and all at the same visual "volume" for usability).
In short—they still don't get it; they are signaling, in conventional ways that most users process subconsciously, thought habits and forms of attention that are not contributing to efficiency and use, but rather detracting/distracting from it. This is the same old KDE with poor, unprofessional design that leads to cognitive clutter. It's not that KDE has "too much going on" but rather that KDE has "too much going on that isn't actually functional and adds nothing to users ability to get things done).