SUMMARY
When using a fractional scaling like 150%, only some apps (kate is a common example but i think it is not a kate bug) when maximized, their size doesn't fill the screen completely, width and height both have one pixel less than the expected size, leaving transparent lines on the right and bottom edges of the application where you can click underlying window or desktop if exist.

STEPS TO REPRODUCE
1. Set display settings to 3840x2160 and 150% scaling, restart computer (or dm maybe) to make changes applied correctly.
2. Open Kate and maximize its window.

OBSERVED RESULT
Kate window width and height is one pixel less than expected, if you go over top right of the window, you will notice close button is not activated, instead underlying window will be clicked if you click like that. It is very annoying, and this bug was not exist before in kate, but it was exist in some other apps, now it came to kate too, without fixing, it just spreads.

EXPECTED RESULT
Kate windows would fill all the available area and no gaps between the right edge of the screen and the window, so you can easily mouse over your mouse to the corner and click without worrying what it will do underlying windows.

SOFTWARE/OS VERSIONS
Linux: Arch-6.9.5
KDE Plasma Version: 6.0.5
KDE Frameworks Version: 6.3.0
Qt Version: 6.7.1

ADDITIONAL INFORMATION
Other apps with same bug i just noticed: okular, qimgv, skanpage... maybe more i guess.