Every single thing you do here is visible to absolutely everyone. By the very nature of how the fediverse works, where everyone can set up a server and participate, there is no way around it.
What you can do to mitigate, if you really feel it is a problem, is to have multiple accounts for different communities. This will limit how much of a profile other users can build on you.
You could also rotate accounts over time, and create new ones every month, for example.