Which is the most compelling evidence that UFOs are NHI’s tech?

What specific piece/s of evidence related to UFO sightings contribute to the compelling argument that these phenomena are not merely to be attributed to glares or weather conditions, but rather represent advanced technological constructs engineered by non-human intelligence (NHI)?

P.S.: sorry for the weird phrasing, but I did not want to explain my view in order not to influence replies, so I used Chat GPT and it decided to get super-formal