I have seen this quite a few times. In some random directories there is usually a .uuid file or directory therein. The directories are nothing special so as to speak. They are mostly random media files or files I have downloaded from somewhere or the other. Then why do these uuid files exist. The filesystem is ext4 and am using Debian buster.
Do the random files include any font files, or files with a filename suffix matching those of any font file types? And does your desktop environment include a tool or library that would produce a preview of font files, or a custom icon for them?
.uuid files in directories like
~/.fontconfig. I guess some sort of font previewer might be doing its job by invoking
fontconfig with a custom directory, and thus cause the
.uuid files be dropped into directories where possible font files exist.