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SUMMARY
Similar to the symptoms described https://bugs.kde.org/show_bug.cgi?id=504848 - tiled windows don't maintain their position (or z-index, but that may be another issue) when moved from one virtual desktop to another, but for this issue I see the behavior when using the "Window One Desktop to the Left" (Right, Up, Down) shortcuts.

STEPS TO REPRODUCE
1. Enable >1 virtual desktop
2. Open a window (e.g. Kwrite) and tile it to one side
3. Move the window to another virtual desktop

OBSERVED RESULT
The window becomes floating, detached from its tiled position

EXPECTED RESULT
The window remains in the same physical position on any virtual desktop

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
(available in the Info Center app, or by running `kinfo` in a terminal window)
Operating System: Fedora Linux 43
KDE Plasma Version: 6.5.5
KDE Frameworks Version: 6.22.0
Qt Version: 6.10.1
Kernel Version: 6.18.8-200.fc43.x86_64 (64-bit)
Graphics Platform: Wayland

ADDITIONAL INFORMATION