The traitor is the 10th titanic commander himself Caribou
Or there's a good chance @CoC: Color of Clowns
is up to something and it's not a traditional traitor but Caribou's crewmate, Shiryu of the Rain, doing the dirty deeds. Coming to snag Vegapunk and pick up his crewmate.
Keep an eye on Stussy too, I still don't trust her.
None of the Punks make sense to me, though. Shaka had them dead to rights in those boots with Seraphim around him, and he... decided to give them a history lecture? Can't be him.
Atlas is out of commission.
York is the most sus at this point, but, it looks like she was just asleep.
Lilith and Edison nearly died fighting, doubt it's them.
Pythagoras was with Shaka and them in the lab the first time the barrier went down. Even if the Punks don't share all thoughts, I'd imagine they're able to tell when another Punk activates something or uses security clearance.
Stussy, Caribou, and Shiryu are my three guesses. We haven't spent nearly enough time with the Punks for a traitor reveal to be interesting, IMO.