Honestly the fediverse is already a bit of a privacy nightmare, and people refuse to take it seriously. Our version of this horror will include your comments and voting activity and likely a bunch of other telemetry which isn't public on reddit. Oh and it won't just be a single "official" AI agent, it will be dozens of them from every corporate or government which wants to build a user database and keep it around forever.
We could bake real privacy protection into our fediverse apps, but the admins and devs seem to have completely punted on this.