HiDPI Scaling on X11 on KDE 6

After installing KDE 6 the scaling on everything seems to be messed up. I have a high dpi display that I have the dpi set to 192. I set it with xrandr --dpi 192. It worked fine until I updated to KDE 6. Now everything KDE seems to be at the default scale of 96 dpi. Chromium and other non KDE applications still work fine and are at the right scale. I use fvwm3 as my wm if that matters.

Any ideas?

You shouldn’t do that. Just remove any xrandr scripts you have and use systemsettings to scale the ui.

I’m not using plasma, just some KDE apps. I am using arch if it matters
This is all that shows in systemsettings if I install it.

The module for the display configuration in systemsettings should be in the kscreen package.

I guess you can try installing that but I don’t think that it will help you in any way. Maybe ask in an arch or fvwm3 related forum for other people who may have a solution for this .

It can be set via x settings / x resources (idk how but there should be a way): High DPI | Qt 6.6

I would also like to note that it was not worth removing the DPI settings, I have a 13.3-inch laptop and on it, using the screen adjustment method, it turns out hell knows what. The icons are huge, the fonts are small, and many other things that are not regulated by resolution. It would be nice to return the DPI setting

Putting Xft.dpi: 192 in ~/.Xresources and restarting X fixed it. The xrandr --dpi 192 in xinitrc was able to be removed

Installing this worked to add the screen settings, but changing it didn’t affect dpi even after restarting X. The setting did show as 200% after restarting x, but there was no change.

yeah! This is what I was expecting.

I had smth very similar after updating my Arch to KDE 6. Has a 200 scale with KDE 5. All dpi scaling went well with KDE 6 besides app bar and many plasma widgets. Cleaning all the plasma config helped to get things back to normal for both X11 and Wayland.
I believe some redundant settings were there like font scaling and cursor scaling or smth.