This is going to be a central question to whatever the law turns out to be. If you post to a group forum of any sort under your real name and a member of the group shares your comments outside the group, is that actually doxxing?

How big is a chat before you can reasonably/legally argue it isn’t private?

I don’t have the answer to these questions. Personally, I would never assume anything I said in a group chat with 10+ participants would be private. In the cited example, where we have a group of 100+ people, I can’t see how that could ever be argued as private communication. If some of them are posting under their real names, I can’t see how they can claim someone else leaked their identity.

But, I’m not writing the law. It will be interesting to see what the government proposes.