Pointing out yet again that Community Notes long precedes Musk's purchase of Twitter. It got going in early 2021; I was one of the first batch to sign up for it, although I think it had been in developments for a year or so before that. January 6 rattled a lot of people at Twitter so I suspect that influenced the timing of the rollout.

Perhaps the confusion is that CN was originally called 'Birdwatch' and people don't realize they're the same thing.