Dolphin will copy video files in trash to /tmp, filling it up and possibly leaving the system without free RAM.
STEPS TO REPRODUCE
1. Move a video file to the trash
2. Open the trash in dolphin
The file will be copied to /tmp and will be kept there
The file should not be copied to /tmp
(available in About System)
KDE Plasma Version: 5.22.5
KDE Frameworks Version: 5.87.0
Qt Version: 5.15.2
I think the files are copied there to generate the thumbnail, but that is not needed at all. Files in trash are just regular files in ~/.local/share/Trash, so the thumbnailer can just access them normally.
*** This bug has been marked as a duplicate of bug 368104 ***