Not sure how unique it is to Academia.SE but it didn't show up in MathOverflow. To get rid of it, I had to click on it which involved giving it access to the microphone. How do I know this website has relinquished this access after I dismissed the duck? I think the duck should go or at least be presented in a more informed way, with opt-in, not opt-out.
The duck never accesses your microphone, even if you say that you have one.
Think about it: If it could access your microphone without a browser-site confirmation, so could every other website, which would be a privacy nightmare.
I've seen it on multiple sites, so that suggests this needs to be brought up on the main meta site.