sure, it's entirely possible that bad actors are deliberately poisoning the well. I don't discount this. it's like frequency jamming though; even if you know the enemy is jamming your comms, you still can't pickup the actual signal if it's below the noise floor.

True, but jamming wouldnt be necessary.

Confirmation bias hacks work by preventing the target from even looking for the signal. Or worse.

This seems not only perfectly plausible, but quite likely.