SUMMARY
Especially the trash.desktop keeps disappearing, but I have seen another .desktop entry that I manually created disappearing from the desktop. The .desktop files are there, but just don't show up on the Desktop. Deleting the file using Dolphin and undoing it (ctrl + Z) makes it reappear on the desktop.

STEPS TO REPRODUCE
1. Create trash.desktop ( like in ADDITIONAL INFORMATION below)
2. Use your computer for a while
3. 

OBSERVED RESULT
Randomly trash.desktop disappears from the desktop.

EXPECTED RESULT
No such thing.

SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma:  6.8.7-arch1-1 (64-bit)
(available in About System)
KDE Plasma Version: 6.0.4
KDE Frameworks Version: 6.1.0
Qt Version: 6.7.0

ADDITIONAL INFORMATION
The content of "trash.desktop"

    [Desktop Entry]
    Name=Trash
    Comment=Contains removed files
    Icon=user-trash-full
    EmptyIcon=user-trash
    Type=Link
    URL=trash:/
    OnlyShowIn=KDE;