I think anyone coming into an online social platform who thinks that any part of it is private, is too naive and/or uneducated to be using that type of platform.
I’m sure there’s parts of platforms which are private, I just don’t think it’s advisable to assume that at any point.
You’re online, interacting with people. If you wanted privacy, don’t be there doing that. Post and behave as if you are publishing everything to a major commercial physical publication. Every post, every comment, every vote, every blocked user. On every one of your accounts.
Otherwise, you’ll get what’s coming to you. And I’m fine with that.