Bug 479662

SUMMARY
***
NOTE: If you are reporting a crash, please try to attach a backtrace with debug symbols.
See https://community.kde.org/Guidelines_and_HOWTOs/Debugging/How_to_create_useful_crash_reports
***

I am completely unable to launch plasma in wayland, and I am completely lost at this point.

Steps I have tried:
1. Specify `QT_QPA_PLUGIN="xcb;wayland-org.kde.kwin.qpa"` in `/etc/environment`
2. Reinstall `qtwayland5`, `qt6-wayland`
3. Install every possible platform plugin for qt (which is probably how I ended up with wayland-org.kde.kwin.qpa)
4. Reinstall kwin

Nothing seems to work. However, upon specifying `QT_DEBUG_PLUGINS=1` in `/etc/environment`, I found this:
```
Jan 11 12:07:39 prizm kwin_wayland_wrapper[59248]: QFactoryLoader::QFactoryLoader() checking directory path "/usr/bin/platforms" ...
Jan 11 12:07:39 prizm kwin_wayland_wrapper[59248]: Cannot load library /usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/KWinQpaPlugin.so: (/usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/KWinQpaPlugin.so: undefined symbol: _ZN15QPlatformWindow17startSystemResizeERK6QPointN2Qt6CornerE, version Qt_5_PRIVATE_API)
Jan 11 12:07:39 prizm kwin_wayland_wrapper[59248]: QLibraryPrivate::loadPlugin failed on "/usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/KWinQpaPlugin.so" : "Cannot load library /usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/KWinQpaPlugin.so: (/usr/lib/x86_64-linux-gnu/qt5/plugins/platforms/KWinQpaPlugin.so: undefined symbol: _ZN15QPlatformWindow17startSystemResizeERK6QPointN2Qt6CornerE, version Qt_5_PRIVATE_API)"
Jan 11 12:07:39 prizm kwin_wayland_wrapper[59248]: qt.qpa.plugin: Could not load the Qt platform plugin "wayland-org.kde.kwin.qpa" in "" even though it was found.
Jan 11 12:07:39 prizm kwin_wayland_wrapper[59248]: This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Jan 11 12:07:39 prizm kwin_wayland_wrapper[59248]: Available platform plugins are: wayland-org.kde.kwin.qpa, dxcb, eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, wayland-egl, wayland, wayland-xcomposite-egl, wayland-xcomposite-glx, xcb, wayland-org.kde.kwin.qpa.
```
Whatever it is, the issue seems to be wayland-org.kde.kwin.qpa. I can't find the package that this is from, so I was curious if anyone could lend a hand.

SOFTWARE/OS VERSIONS
Linux: Kubuntu 23.10
KDE Plasma Version: 5.27.10
KDE Frameworks Version: 5.112.0
Qt Version: 5.15.10
Kernel: 6.5.0-14-generic (64-bit)

ADDITIONAL INFORMATION
<!!!> I also have the KDE Backports PPA, which allows me to keep my KDE suite up to date. I suspect this may be a reason I am having this problem, and should probably create a fresh install come Plasma 6.