Maybe it refers to when Maul is talking to the members of the Syndicate in the hologram, there's Dryden Vos on the far right. Paul Bettany's character from Solo. I think that's who it is. Considering Maul was in the hologram in Solo, it is most likely Vos.
Great fucking episode. I can only reiterate what Drew and others have said. This is what SW is, and should be going forward. Also, listen to the musical queues in the episode. You can hear the Emperor's theme when Kenobi is talking about Anakin and the Chancellor. Just amazing. Not only that, the musical queue during the opening credits was eerily similar to the beginning of Close Encounters. The queues in the last episode were great too, when Anakin is on the bridge staring down the droid army you can hear the music to Luke's salute off the desert skiff when he signaled R2. Good details.
Speaking of the opening credits and the show being cinematic, hell, the opening itself is just like the opening of 1977 Star Wars. Green Lucasfilm Limited font on a black screen fading into a red letter box for Clone Wars. That's retro! Awesome, just fucking awesome.
I really want to see an Ahsoka and Rex buddy series/movie.
Can't wait until next week. This has been so fucking awesome.