Created attachment 164725 [details]
Output from strace plasmashell, exiting immediately after startup.

SUMMARY
If I open "too many" windows, plasmashell exits with the message
> The Wayland connection broke. Did the Wayland compositor die?
resulting in the panels and root window background disappearing, etc.
plasmashell does not appear to crash - there is no indication of a coredump - it simple exits with status 1.

I'm not sure how many windows are "too many".  I was roughly guessing about 100.  xwininfo currently says the root window has 165 children, if that helps - but I see what appear to be a lot of duplicates in its list.
When I discovered what was happening, I started running plasmashell from an xterm so that (a) I could continue working, and (b) so that I could see its output.  Sometimes there are additional error messages before the one shown above, but that is the only one that's consistent.
It seems that when I'm near the limit, plasmashell becomes increasing unstable as more windows are opened.  Beyond a certain point, it exits immediately after it starts.  If I then close some windows, I can restart plasmashell and it will run again until I open more windows.

I'm attaching output from plasmashell running under strace.  In its current state, it exits immediately after starting it, with no other message than the one shown above.

STEPS TO REPRODUCE
1. Start session, open applications (web browser, numerous xterms, gitk, Ardour, okular, ...).
2. Continue opening windows, keeping an eye on the panel containing task manager (for me this is at the bottom of the screen)...
3. 

OBSERVED RESULT
With somewhere between 50 and 150 open windows, an additional window seems to cause plasmashell to exit with zero or more error messages, always ending in the on cited above.

EXPECTED RESULT
Session continues to operate normally; panels and their apps continue to function, and I'm blissfully unaware of plasmashell. :-)

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: Fedora 38
(available in About System)
KDE Plasma Version: 
KDE Frameworks Version: 
Qt Version: 

ADDITIONAL INFORMATION
Hardware: System76 Gazelle (gaze17); Intel i7-12700H; 64 GiB RAM
I have not installed proprietary nVidia drivers, and it appears I'm running nouveau - I see it in lsmod's output.  (I've previously played around with switching between Intel and nVidia GPUs and didn't remember how I left it.)