Similar observation a few years ago in the sea sky: some ligh moving very high, with a strange flying pattern (like a very fast bee), for 20 minutes, above my head, then disapearing. No apparent light beam, support for light reflection, animal presence or mechanical vehicule. Clear weather conditions.

It was, to my eyes, an object that was flying and that I couldn't identify. So UFO applies.

The problem is not seing those.

The problem is making interpretations out of those.

Humans often prefer to create explanations than say they just don't know.

Centuries ago, somebody spot lightning and said it was Thor. We are mocking them now, but we are doing the same.