SUMMARY
Any file printed using KDE's system dialog, through any application tested (Gwenview RPM, KWrite RPM, etc.) is always printed portrait orientation. Selection of the Landscape orientation in the Printer's "Properties" window does not affect orientation actually printed.

Applications which implement different "Print" GUI than what is provided by KDE (Gnome Image Viewer RPM, Firefox Browser & forks, LibreOffice, etc.) all print in the correct orientation.

Printing to PDF is not impacted by this bug, only printing to physical printers.

STEPS TO REPRODUCE
1. In any application which uses KDE's native print dialog, open the print dialog (e.g. File > Print) 
2. With target printer selected in dropdown, select "Properties" button
3. In popup window: "Page" tab -> "Orientation" -> Select "Landscape" radio button.
4. Click "OK" button to accept changes and close popup
5. Click "Print" button to send job to printer

OBSERVED RESULT
Job is printed in portrait orientation, but still cropped for landscape printing, with blank space at the top and bottom of the page(s). If job filled width of a landscape page, sides of job are off the edge of the paper.

EXPECTED RESULT
Job should be printed in landscape orientation.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora Linux 41, KDE Spin
KDE Plasma Version: 6.3.4
KDE Frameworks Version: 6.12.0
Qt Version: 6.8.2

ADDITIONAL INFORMATION
Printers Used:
1. Epson EcoTank ET-3850 (driverless)
ipps://EPSON%20ET-3850%20Series._ipps._tcp.local/

2. HP Envy 4520 (driverless)
ipps://HP40B0348C3EDB.local:443/ipp/print