Hot Air's John Sexton suggests two bases for speculation about the leaker,
https://hotair.com/john-s-2/2022/05/03/the-best-argument-that-the-draft-decision-was-leaked-by-a-progressive-n466863 : 1. Who benefits; 2. What sort of person would do such a thing. IMO, in either case, it's a Prog.
First, the timing is totally wrong, by 4 or 5 weeks, for Proggies' claim that it was intended to distract from Pelosiroo's Show Trial Kommittee. OTOH, it is pressure on justices who voted to overturn to change their votes, rallies Pro-Aborts to riot against the decision, threaten and possibly try to assassinate justices who voted to overturn, and invade the Supreme Court building on the day the decision is announced.
Second, it is Progs who continually denounce the US Constitution as anti-democratic, racist, fundamentally flawed, yada, yada, yada. It is Progs who regularly riot, murder, burn, and loot when they don't get their way.