YouTube says this feature will appear when you are listening to mixes and radio stations.
It may just yammer at you annoyingly with AI misspeaks between songs and not during them.
Some here are claiming that "you are not the customer, you are the product". This applies only to people who are listening to YouTube for free, and are already getting hit with commercials. It you pay for YouTube Music (if they are still calling it that, it is hard to keep up) then you really are the customer, not the product.
If this annoying "feature" gets turned on (and cannot be permanently turned off) then my YouTube Music subscription goes away.