

PieFed has a default list of domains/instances that are blocked when you do a fresh install for a brand new instance. A critical difference between PieFed and the Tesseract blocks is that any of the blocks in PieFed are completely visible to, and under the control of the admins of the instance. So, ultimately, it is just an out-of-the-box default, but the instance admins always have ultimate control over moderation/federation choices. This Tesseract stuff is taking those powers away from the admins.
FYI, next version of PieFed has an “Unban All” button for clearing all domain bans to try to make this easier.
Screenshot from my instance: