Uh huh. If aliens were able to reach our solar system, do you think they would give one shit about being seen by a primitive civilization with zero space defenses?
If we're talking about signs of alien life from deep space scans, do you really think that the scientists that found this evidence, who have spent their life pursuing the better understanding of the galaxy, would keep quiet about it at the behest of whatever government?
Life isn't that interesting. There's no massive multi-government conspiracy. We couldn't even get governments to shut down borders or enforce mandates on wearing mask when a global pandemic of unknown severity was ongoing.
You've watched too much fictional media if you think any conspiracy of that level is remotely plausible.