contenthash is really the location of the file.
select contenthash,filearea,filename,filesize from `mdl_files` where filename like "%.mbz%" order by filesize DESC
is meta data and will return rows like:
496b7ed2c090160c8d955887f7834c244e8e492b course backup-moodle2-course-593-dim-20200522-1149.mbz 30168358282
The contenthash: 496b7ed2c090160c8d955887f7834c244e8e492b
is the location of the file in moodledata/filedir/ and filename ... no humanly recognizable filenames in /moodledata/filedir/
From command line on Linux one could use file -b on that file to see it's mimetype.