I also blame Qt for not being able to modify the app window header in Ubuntu.

When I started to use Linux more than two decades ago, Qt's license was not considered free software friendly. Because I didn't want proprietary software, I avoided KDE and Qt applications. I know the situation changed after a few years but it stuck with me.

Controversy erupted around 1998 when it became clear that the K Desktop Environment was going to become one of the leading desktop environments for Linux. As it was based on Qt, many people in the free software movement worried that an essential piece of one of their major operating systems would be proprietary.

Plus, it was much easier at that time to have themes and "rice" my desktop using only GTK apps.

So it's petty but even to this day, I kept the old habit and still avoid Qt applications.

I just avoid gtk. And avoided scaling since I don't buy monitors with to high resolution for my eyes.

Why is it a problem that there are "bits" of light mode in the UI when switching from dark mode? You'd think you'd want all of the bits to be light mode then. Is that the issue, that not all bits are light mode?

I kinda miss my Gnome DE. Ive Been using KDE Plasma after upgrading Debian which it now officially supports but I've been experiencing crashes and bugs... This surprises me on a Debian machine.

I'm personally GTK gang. I only use like 1 or 2 qt apps because there's no alternative and i don't even bother theming them anymore.

KDE by default doesn't have a mac style global menu. If the third party extension that provides this looks fancy but doesn't work perfectly ask the devs to do more free work or roll up your sleeves. In any case its not part of KDE.

If you use a proper style sheet/dark theme for both QT and GTK and set flatpak to use it you really shouldn't have any complaints about dark themes save for websites. Trying to make websites all dark themed is a fools errand. You'll eventually find that some don't style right if you force it.

Use integer scaling. Buy devices that are 4K at 24-32 or 1080p at 11-14" you know the most common sizes?

I don't understand why any user would have to care or even know what GUI toolkit an app uses.

I don't know why the burden is put on the user/DE. You shouldn't have to care about what GUI toolkit your DE uses either.

DE and themes should be decoupled from eachother. So the user can install whatever "theming system" they want, and GUI toolkits should aim to support as many theming systems as practical.

GUI toolkits are implementation details, the user doesn't care about implementation, it cares about what it sees. And what it sees is the colors and icons.