Jacques Vallee, a noted computer scientist in his own right, is one of the best reads if you're interested in this stuff. He's not a crackpot and doesn't seem to be pushing an agenda one way or another.
"Vallée proposes that there is a genuine UFO phenomenon, partly associated with a form of non-human consciousness that manipulates space and time. The phenomenon has been active throughout human history, and seems to masquerade in various forms to different cultures. In his opinion, the intelligence behind the phenomenon attempts social manipulation by using deception on the humans with whom they interact."
Also, I've read his books. Wikipedia quotes don't really give the same impression as his writing.
https://en.wikipedia.org/wiki/2006_O%27Hare_International_Ai...
Obviously rainbows are an example of a shared hallucination and the phenomena manifests differently dependent on the observer's viewing angle. At the moment I'm not convinced these aren't unexplained atmospheric phenomena because I've never seen one. I know some ideas put forth include ball lightning for at least some UFOs. Assuming these cases to involve intelligence may just be our misinterpretation of the phenomena.
That's.. unspecific. The atmospheric research community would probably be highly interested in more details.
As a sidenote I've noticed a lot of people in the UFO/ET community no longer believe ETs are from another planet. Most seem to think they're "interdimensional" beings (which just sounds to me like sciencey way of saying supernatural).
https://www.jp-petit.org/science/gal_port/Von_Ludwiger.htm
He proceeds to bash Vallée, Hynek, and some other lesser known ufologists. It's in French but Google Translate is very good nowadays.