If you can tell me a bit more, I might be able to help you figure out what it is: did you find this file or see the name? What apps or devices were you using at the time? Do you have a link to where this file is hosted?

An from a specific software or website that isn't indexed by search engines.

That string is a (Universally Unique Identifier), which is typically used by computers to label files uniquely. Because of this, it’s likely: A private file from your own device or cloud storage. A temporary file or cache item generated by an app.