is 4WKSHXTL7 an id for any file sharing service?

The string "4WKSHXTL7" doesn't appear to be a commonly recognized identifier for any specific file-sharing service that I am aware of. File-sharing services often have their own unique formats for identifiers, and details can vary widely between platforms. If you encounter this string in relation to a specific service, it's best to check that service's documentation or support resources for more information on how their identifiers work.