A long time ago I heard it posited that one possible answer to Fermi’s paradox (”If aliens are out there, why haven’t we heard from them?”) is that they have perfected the ability to conceal their communications, so we can’t detect them. If we could find the signals containing their communications, we couldn’t get anything from the signal.
My posit on why we don’t hear from aliens is that any technology that can communicate across the vast distances of space is not going to be radio.
Whatever technology the aliens have it is to radio what radio was to semaphore flags.