SUMMARY
I have just upgraded to Fedora 43. In previous editions I have not been able to use plasma on wayland. A few core applications failed to work. So with this recent upgrade to Fedora 43 I'm re-evaluating.

This bug is specifically about Firefox not working properly under Plasma Wayland

STEPS TO REPRODUCE
1. Start firefox from a konsole

OBSERVED RESULT
1. Firefox will start to restore the windows from a previous run (5 in my case), but while opening these, it will get stuck in some kind of flickering pattern and the open windows will not properly refresh. Instead the whole of firefox windows will get stuck at displaying garbage. Aside from entering the password to unlock firefox' password store, no further interaction with firefox is still possible.

2. The console window shows the following output:
$ firefox
[GFX1]: Error in eglSetDamageRegion: 0x3009
...
repeated many times
...
[GFX1]: Error in eglSetDamageRegion: 0x3009
[GFX1-]: Failed to make render context current, can't draw.
...
repeated many times
...
[GFX1-]: Failed to make render context current, can't draw.

<At this point I hit ctrl-C to abort the session>

Exiting due to channel error.
...
repeated +/-10 times
...
Exiting due to channel error.

3. While firefox is running in this erroneous state, I can't properly start any other applications. That is, they will start, and will appear as running in the task bar, but their windows won't display. I tried with digikam and this gave the following output in the terminal during faulty startup:

$ digikam
kf.i18n: KCatalog being used without a Q*Application instance. Some translations won't work
digikam.dimg: ICM Wayland: the device is not a screen: "/org/freedesktop/ColorManager/devices/cups_Brother_TD_4100N"
GBM is not supported with the current configuration. Fallback to Vulkan rendering in Chromium.
qt.multimedia.ffmpeg: Using Qt multimedia with FFmpeg version 7.1.2 GPL version 3 or later
parseSampleFormat: parse error "Object: size 144, type Spa:Pod:Object:Param:Format (262147), id Spa:Enum:ParamId:EnumFormat (3)" "  Prop: key Spa:Pod:Object:Param:Format:mediaType (1), flags 00000000" "    Id 1        (Spa:Enum:MediaType:audio)" "  Prop: key Spa:Pod:Object:Param:Format:mediaSubtype (2), flags 00000000" "    Id 3        (Spa:Enum:MediaSubtype:iec958)" "  Prop: key Spa:Pod:Object:Param:Format:Audio:iec958Codec (65542), flags 00000000" "    Choice: type Spa:Enum:Choice:Enum, flags 00000000 24 4" "      Id 1        (Spa:Enum:AudioIEC958Codec:PCM)" "      Id 1        (Spa:Enum:AudioIEC958Codec:PCM)" "  Prop: key Spa:Pod:Object:Param:Format:Audio:rate (65539), flags 00000000" "    Choice: type Spa:Enum:Choice:Range, flags 00000000 28 4" "      Int 48000" "      Int 32000" "      Int 48000"
QWaylandGLContext::makeCurrent: eglError: 0x3003, this: 0x55c33353ab10 

QRhiGles2: Failed to make context current. Expect bad things to happen.
Failed to create QRhi for QBackingStoreRhiSupport
kf.xmlgui: Unhandled container to remove :  Digikam::DigikamApp

EXPECTED RESULT
Firefox just works

SOFTWARE/OS VERSIONS
Operating System: Fedora Linux 43
KDE Plasma Version: 6.5.2
KDE Frameworks Version: 6.19.0
Qt Version: 6.10.0
Kernel Version: 6.17.7-300.fc43.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 8 × Intel® Core™ i7-6700K CPU @ 4.00GHz
Memory: 48 GiB of RAM (47.0 GiB usable)
Graphics Processor: NVIDIA GeForce GT 1030