If you haven't got a version (any version) of Joplin installed on your system it is not so much a "mystery of life" as a serious bug. You are suggesting that the portable version can under unknown conditions store note data in the user account files on the host machine when that version is expressly designed not to do so.
The portable version is engineered to store its data in a folder called JoplinProfile located in the same folder as the JoplinPortable.exe file. In your case that is on your "E" drive. The installed version stores its data in a .config\joplin-desktop folder in the logged in user's data folders.
Whilst you may not have installed v3.3.3 could you have installed an earlier version some time ago and forgotten?
Follow your "DOG food" link to open up the "empty" version of Joplin and click Help > About Joplin. This will show the version. Also only an installed version will be listed in Windows under Settings > Apps > Installed Apps.