A lot of credible people have left Twitter - it has gotten much more overrun by bots and a lot of very hateful accounts have been reinstated and protected. It is a poor platform for reasonable discussion and I think it's fair to say it's been stifling open expression. The value is disappearing.
I think it was an appropriate answer at the heart of the matter - most credible people are leaving the platform due to the degradation of quality on it. For a literal example of a ban though there are few examples better than Dell Cameron[1].
