Spooky, because I'm conscious about privacy & regularly check that my tracking is limited to only the things that I explicitly allow. Yet, somehow Google managed to flip it on for a few weeks over the past 2 years.

As someone else pointed out, 'app updates' or 'adding a new device' resets these settings. If I had one of those "always on" devices, it would have a lot more conversations stored, some that don't even start with the hotword.