It's The ATmosphere network, Bluesky is just one of many Federated "servers" running on ATproto protocol.

It's part of the larger/umbrella term SocialWeb (a.k.a. OpenSocial ) where the objective (s. 2005) is to BringDownTheWalls (and BuildBridges ).

DDFON MycelialWeb

The original post shown in the screenshot.

Paul Frazee's Monster (@pfrazee.com)