Fractional scaling (you can only set the screen scaling to integers so: 100%, 200%, when the ideal is probably around 150% in a 13 inch screen). I made it 100% and used a font scaling factor of <1 in Gnome Tweaks. I think this is not an issue with KDE
That's a Gnome problem, apparently their fix will be to scale elements of the UI as if they were fonts which, according to them, will work better than fractional scaling and will fix the blurriness on all fractionally scaled apps.