It will come out, eventually.
“I personally have a pretty good idea who is responsible, but that’s different from the level of proof that is needed to name somebody,” Alito said: “It was a part of an effort to prevent the Dobbs draft … from becoming the decision of the court. And that’s how it was used for those six weeks by people on the outside — as part of the campaign to try to intimidate the court.” [emphasis added]
… He also called it infuriating that some people believed a conservative justice may have leaked the decision. “Look, this made us targets of assassination. Would I do that to myself? Would the five of us have done that to ourselves? It’s quite implausible.”