SUMMARY

In wayland on 5.21, you cannot drag a window to another desktop using KWin shortcuts to switch the desktop. The shortcuts don't work while holding a window, but function fine if you aren't.

Shortcut located at:
Settings -> Workspace -> Shortcuts -> System Services -> KWin -> "Switch One Desktop to the Right"

STEPS TO REPRODUCE
1. Bind Switch One Desktop to the Right to any key, I use Meta+Tab.

2. Next, try to "drag" a window to a different desktop by holding a window and then hitting the next-desktop key.

3. When you press your "Switch One Desktop to the Right" key, nothing will happen if you are holding a window. If you are not holding a window, then the desktop will switch as expected.

OBSERVED RESULT
Switch-Desktop shortcut keys do not work while holding/dragging a window in Wayland. The key functions as expected otherwise.

EXPECTED RESULT
Switch Desktop shortcut keys should switch to your next desktop while dragging a window, allowing you to drag a window to a different desktop.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch
KDE Plasma Version: 5.21.0
KDE Frameworks Version: 5.79.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION
GPU: Radeon RX 590
Two monitors: {1920x1080@60hz-Left, 2560x1440@144hz-Right}