Created attachment 181801 [details]
journalctl logs showing xwayland having trouble after resume

SUMMARY
When resuming from sleep with a UE5-based game running, all Xwayland apps will crash. This ONLY happens if the "Lock after waking from sleep" setting is disabled. I've been able to reproduce this easily with Clair Obscur: Expedition 33 and Lords of the Fallen. Sleep was triggered via Steam's Big Picture mode.

If lock screen is configured to lock after waking up, for some reason this prevents the crash. If I am not running a UE5 game, then system resumes fine as well, regardless of whether lockscreen is enabled or not. I was able to successfully resume Last of Us Part 2 for example. So it seems it is the combination of UE5 + lockscreen disabled that's the main trigger here.

After the crash happens, Xwayland gets into a weird state. Games no longer fullscreen properly, Steam's Big Picture mode stays in a window when activated.

STEPS TO REPRODUCE
1. Disable "lock after waking from sleep" in System Settings -> Screen Locking
2. Launch a few Xwayland apps in the background (VSCode, Element Desktop, etc.)
3. Launch Steam and start Big Picture mode
4. Launch a UE5 game and load a save.
5. Go into the Big Picture overlay with your controller or via Shift + Tab and suspend your system via the power menu
6. Turn on your system again
7. Notice that the game AND all the background Xwayland apps have disappeared

OBSERVED RESULT
The game and all background Xwayland apps crash

EXPECTED RESULT
System resumes fine.

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.3.5
KDE Frameworks Version: 6.14.0
Qt Version: 6.9.0
Kernel Version: 6.14.7-arch2-1 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 9800X3D 8-Core Processor
Memory: 62.4 GiB of RAM
Graphics Processor: NVIDIA GeForce RTX 3090 w/ 575.51.02 drivers
Manufacturer: Gigabyte Technology Co., Ltd.
Product Name: X870E AORUS ELITE WIFI7

ADDITIONAL INFORMATION
Journalctl has the following suspicious xwayland messages:
```
May 27 15:19:06 kwin_wayland_wrapper[1333]: XWAYLAND: error marshalling arguments for lock_pointer (signature noo?ou): null value passed for arg 2
May 27 15:19:06 kwin_wayland_wrapper[1333]: XWAYLAND: Error marshalling request: Invalid argument
May 27 15:19:06 kwin_wayland_wrapper[1333]: (EE) failed to write to Xwayland fd: Invalid argument
May 27 15:19:06 steam[1862]: X connection to :0 broken (explicit kill or server shutdown).
May 27 15:19:06 kwin_wayland[1026]: kwin_xwl: The X11 connection broke (error 1)
May 27 15:19:06 kded6[1484]: X connection to :0 broken (explicit kill or server shutdown).
May 27 15:19:06 steam[1862]: X connection to :0 broken (explicit kill or server shutdown).
May 27 15:19:06 steam[1862]: X connection to :0 broken (explicit kill or server shutdown).
May 27 15:19:06 steam[1862]: X connection to :0 broken (explicit kill or server shutdown).
May 27 15:19:06 steam[1862]: X connection to :0 broken (explicit kill or server shutdown).
May 27 15:19:06 steam[1862]: X connection to :0 broken (explicit kill or server shutdown).
May 27 15:19:06 steam[1862]: X connection to :0 broken (explicit kill or server shutdown).
May 27 15:19:06 steam[1862]: X connection to :0 broken (explicit kill or server shutdown).
May 27 15:19:06 steam[1862]: X connection to :0 broken (explicit kill or server shutdown).
May 27 15:19:06 steam[1862]: X connection to :0 broken (explicit kill or server shutdown).
May 27 15:19:06 steam[1862]: X connection to :0 broken (explicit kill or server shutdown).
```

I've attached the logs starting from the start of that suspend.