By shadowban, if we mean that a platform stops to recommend your content in other people’s feeds, then yes, a decentralized network solves this particular problem. Here we are talking about global public discussions.

The concept of ownership matters. Nobody owns the global and it’s public space. Nobody is the creator of the universe.

However, group chats are public but not global. Groups have clear ownerships.

Constraining a group chat in a finite set of servers is a desired property.

A member could be banned by both the physical server owner or the logical group owner.

In case the group owner is banned by the server, this owner can migrate all the data to another server and invite all members back.