Signatures of alien technology like say....odd objects flying in formation or separately around military and civilian aircraft?

Which they've been doing for decades.

Those sorts of signatures of alien technology?

Or

An odd acting object that enters the solar system that gets immediately classified by astronomers as an asteroid or comet even though it doesn't really look like or act like either?

And when someone mentions that it could possibly be alien technology they get mocked and denigrated.

So the problem with the "signatures of alien technology" idea being taken seriously is that apparently in the absence of a flashing neon sign saying, "hey guys this is alien technology" astronomers and other scientists and others due to the fear of ostracism etc...will immediately classify everything as a naturally occurring object making it impossible to study even the possibility of observing alien technology.