“We identified this as an issue, it was a mistake, we fixed it within 24 hours,” Dorsey said. “We want to be clear that we do not shadow ban according to political ideology or viewpoint. We do rank the timeline and we do that with the principle of relevance, but all the content is still there — you just have to do more work to see it.”
In other words, Twitter does use shadow ban methods. A shadow ban is one where the user is permitted to continue posting, but what ever they post is hidden from other users. In this way, the user is unaware that they have been banned from the platform. Effectively it is secret censorship.