Created attachment 170896 [details]
Screen recording of the bug using VLC

SUMMARY
With git master Plasma 6.2 compiled today using kdesrc-build, if an app plays media and uses MPRIS so the media player applet in the system tray appears (so far I tried Firefox with the Plasma Integration extension, VLC and Elisa), and then the app is closed (or in the case of Firefox closing the tab that was playing media), instead of just the media player applet deactivating the whole system tray disappears instead, at least visually.

There is still a small invisible space where I can right click and have the context menu for the system tray appear so that I can open the system tray configuration dialog, but I can no longer access any of the applets/tray icons in that state, unless I restart plasmashell.

Disabling the media player applet completely works around the problem, but not just having it be always hidden instead of shown when relevant or always shown.

STEPS TO REPRODUCE
1. Play some media in an app that supports MPRIS (at least VLC, Elisa, Firefox with the Plasma Integration extension)
2. Close the media player app

OBSERVED RESULT
The system tray disappears from view, and the tray icons are inaccessible.

EXPECTED RESULT
Only the media player applet disappears (if set to "Show when relevant").

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.1.80
KDE Frameworks Version: 6.4.0
Qt Version: 6.7.1
Kernel Version: 6.9.5-zen1-1-zen (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 6800H with Radeon Graphics
Memory: 30.6 GiB of RAM
Graphics Processor: AMD Radeon 680M

ADDITIONAL INFORMATION
I also tried the KDE neon-unstable-20240623-1119.iso live image in a VM, but I was unable to reproduce it there, so it looks like something specific to my system somehow?

plasma-workspace is at commit d7caec38eef9d8758463d026aca1e0da15b6289f, and plasma-desktop is at commit 5d60849477e814e37d557996c1ef3eeab0c62ca1.