SUMMARY
In Dolphin, selecting a lot of files, copying (or cutting) them, and pasting them into another directory very often results in only a subset of the files being copied/moved. This can be more easily seen when cutting the files, since while most of the file thumbnails will be grayed out to indicate they've been cut, some of them might not be grayed out.

STEPS TO REPRODUCE
1. Select a lot of files in directory A.
2. Cut the files by pressing Ctrl+X.

OBSERVED RESULT
Some of the selected files do not have grayed-out (desaturated) thumbnails, indicating they haven't actually been cut. Which files, if any, changes every time Ctrl+X is cut.

EXPECTED RESULT
All selected files are cut, with corresponding grayed-out thumbnails.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Gentoo Linux, Kernel 6.4.8
KDE Plasma Version: 5.27.7
KDE Frameworks Version: 5.108.0
Qt Version: 5.15.10