https://canvas.fediverse.events/
Canvas is a collaborative pixel canvas for the Fediverse! It's live until July 20th @ 4am UTC!
Socials
In addition to what grant said. Cursors dont show and arent sent when logged out or when on mobile and are anonymous so people can't tell whos cursor is who. Just a fun thing to add some activity to the canvas and make it feel more like a community instead of you placing pixels into a void