Einstein was not a member of the Manhattan Project. He had no information to leak. In any event, his name does not appear in any of the Soviet files as a possible source. He was close to many people who were sources, though, or attempted sources, but that was because he ran in a lot of different circles. There is no reason to suspect he ever intentionally leaked any information about the atomic bomb project (what little that he had any knowledge of).

While I don't have the expertise to answer, it would seem your premise is invalid, as this answer by u/restricteddata to Why was Einstein not heavily involved in the Manhattan Project? discusses why he was not involved

Additionally, Albert Einstein and the Manhattan Project talks more about the topic (again by u/restricteddata)

As u/Holy_Shit_HeckHounds points out, the premise is wrong: Einstein was not involved in the Manhattan project, as he had often uttered decidedly pacifist views, and while he supported and even called for development of nuclear weapons before Germany did, he was not a general supporter of bombing raids.